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US2778718A - Comminuted coal fines and method of comminuting agglomerated coal fines - Google Patents

Comminuted coal fines and method of comminuting agglomerated coal fines Download PDF

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US2778718A
US2778718A US520631A US52063155A US2778718A US 2778718 A US2778718 A US 2778718A US 520631 A US520631 A US 520631A US 52063155 A US52063155 A US 52063155A US 2778718 A US2778718 A US 2778718A
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silt
coal
weight
water
spent sulfite
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Hartmann Waldemar
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
    • B03D1/00—Flotation
    • B03D1/001—Flotation agents
    • B03D1/004—Organic compounds
    • B03D1/016—Macromolecular compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
    • B03D1/00—Flotation
    • B03D1/001—Flotation agents
    • B03D1/004—Organic compounds
    • B03D1/012—Organic compounds containing sulfur
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
    • B03D2203/00—Specified materials treated by the flotation agents; Specified applications
    • B03D2203/02—Ores
    • B03D2203/04—Non-sulfide ores
    • B03D2203/08—Coal ores, fly ash or soot

Definitions

  • This invention relates to the processing of agglomerated coal fines and, more particularly, to the treatment of agglomerated coal fines with spent sulfite liquor.
  • Silt is the final product resulting from the processing of coal, for example, anthracite silt comes from the preparation of run-of-mine anthracite.
  • This run-of-mine coal is processed through a coal breaker in which it passes over a bull shaker.
  • the bull shaker segregates the larger lumps of coal and sends them through crushing operations to a reduction in size.
  • the crushed coal, together with the segregated run-of-mine coal, are then fed to a set of shaker screens which classify the lumps of coal according,
  • buckwheat #4 which will pass through a screen having mesh openings of of an inch and will pass over a screen having mesh openings of of aninch.
  • Further screening of the material that passes through mesh openings of of an inch produces buckwheat #5 which are pieces of coal that pass through a screen having openings of 7 of an inch and over a screen having openings of of an inch. The remaining coal is known as anthralarger particle size.
  • the anthracite silt contains particles in the following range of sizes:
  • a concentration of the ZOO-mesh silt occurs mostly at the end of a period of breaker operation, such as after a shift or a days run.
  • the ZOO-mesh particles are so fine in body that a normal breaker operation will tend to accumulate them in various settling tanks and traps provided for that purpose.
  • this accumulation is removed by flushing the surfaces with a sluice of water through the breaker equipment. This sluice of water carries the ZOO-mesh particles into the culm bank in which the silt is accumulated.
  • the fine coal of the ZOil-mesh particles is deposited in a layer, as a result of this flushing of the material.
  • the silt bank .on which the silt is accumulated thus contains a range of co-particle sizes with interspersed concentrations of ZOO-mesh particles in layers. These layers of the concentrated --200-mesh particles contain a tenacious adhesiveness and stubbornly resist eomminution.
  • the variety of Anlagenlesizes in the silt is a product of factors in the operation of the classification, such as the stage of the operation during which the silt is deposited.
  • the coal dust from the classification operation is carried to the silt bank by a liquid medium, such as water.
  • This liquid medium carries the silt particles by floatation and most of the liquid drains off the silt bank leaving the coal particles as a deposition.
  • the ZOO-mesh particles are agglomerated by adhesion so badly after collection in a silt bank that the coal cannot be processed. It will not dump out of cars, it forms a solid coating over the mesh of shaker screens and it coats or packs in bins and in feed pipes.
  • the +200-mesh particles and larger particles also exhibit these properties to some degree.
  • the -200-mesh particles form a substance which is impossible to handle by ordinary means even when mixed with coal fines of a Accordingly, quantities of fines and particularly coal fines having particles of ZOD-mesh cannot beprocessed for combustion economically.
  • Another object of this invention is to provide a method of decreasing adhesiveness in agglomerated fine particles of coal.
  • a still further object of this invention is to provide a means and method for decreasing adhesiveness in agglomerated particles which have had an original size of passing through a fl -mesh screen.
  • this invention provides treating agglomerated fines of a size that will pass a of an inch screen aperture and produce .
  • a comminutible product from said agglomerated fine coal silt which can be handled in normal coal silt handling equipment.
  • the comminutibility is effected at least in part by a decrease of the adhesiveness of the ZOO-mesh particles. This comminution is achieved by mixing the agglomerated coal silt with a small percentage of spent sulfite.
  • Spent sulfite is a compound which is made up principally of calcium lignosulfonate. It also may contain sodium lignosulfonate in a substantial proportion, together with certain sugar degradation products. Stated otherwise, it may be considered for the purpose of this description that spent sulfite in general refers to the complex mixture of the salts of low molecular weight of lignosulfonic acids and the alkaline hydrolysis products of pentoses and hexoses which are extracted from coniferous woods in the sulfite pulping process. The spent sulfite liquor also contains tannin and ash in appreciable percentages.
  • the spent sulfite i e liquor is a solution of the spent sulfite solidsin water. ig e The liquor is about half water by weight.
  • the specific 9 spent sulfite compounds referred to herein are defined Ca mum OX1 e as to composition in greater detail below.
  • Spent sulfite is commercially available in llquld and powdered form in the products of several companies.
  • 15 Cofiee colored viscous liquid 4 The following Table I sets forth the products available Specific gravity (60 F./60 F.), 1.24 as identified by their trademark names and associated Baum, 28.5 with the supplying companies.
  • Viscosity 175 centipoises 20 C. (60 R. P. M. Brookfield) Boiling point, 212 F.
  • Composition (on moisture free basis) Calcium lignosulfonate, percent:
  • This invention provides for a processing of silt which changes the silt from a tenaciously adhering agglomeration of the particles into a material which is either in comminuted form, or is comminutible having decreased adhesiveness.
  • the original agglomerated silt is in a physical condition which prevents it from passing through normal classifying shaker or vibrator screens. It also is a material which will cling to the walls and surfaces of a retaining receptacle and resist or defy removal. Such properties of silt render it prohibitively difficult to han dle.
  • these properties of the agglomerated silt may be counteracted by a mixing of spent sulfite in the agglomerated material. This mixing or other incorporation of the spent sulfite in the agglomerated material removes the objectionable properties and allows the silt to become a substance which can be processed for further use, such as combustion.
  • the amount of spent sulfite compound, which must be mixed or otherwise incorporated with the agglomerated silt is related to the percentage of moisture in the silt.
  • the percentage of spent sulfite is also dependent upon the average fineness of the silt and the procedure used in the separation of the silt from the other coal.
  • the flotation process of separating the coal particles may use instead of water such liquids as fuel oil, pine oil, alcohol or kerosene in separating sizes below buckwheat #4 and #5.
  • the use of such flotation media influences the amount of spent sulfite necessary to bring about a comminution of the silt resulting from said previous separation by flotation.
  • the average fineness of the particles in the silt is determinative of the amount of spent sulfite necessary in bringing about satisfactory comminutibility in that as a rule the finer the particles in the silt, the greater the amount of spent sulfite necessary to produce comminutibility.
  • the liquid content of the silt material is closely corre lated to the relative amount of spent sulfite needed. It has been deprmined, when the comminuting material i mad up of rZOQ mesh Pa t cle in a glomerated sendition, that spent sulfite liquor in a ran e 9f from 0.2% to 20% of the water content of the silt will produge the comminuting eifect of this invention.
  • a silt containing a substantial proportion of -200-mesh particles and not less than 10% by weight of water when treated with from 002% to 2% of spent sulfite liquor will lose its property of clinging to surfaces of coal handling equip ment.
  • This process may be used for treating silt containing up to 30% by weight of water.
  • the percent of spent sulfite liquor ranges from 006% to 6% by weight of the silt treated.
  • the silt containing these percentages of water, when treated with the respective percentages of spent sulfite liquor will result in a product which forms easily breakable lumps and has lost the objectionable adhesiveness, so as to not stick to metal surfaces.
  • Larger percentages of the spent sulfite liquor will result in a product which is sloppy and which contains an excess of moisture.
  • the product Will not be comminuted particles, having a relatively dry nature, but will be more in the nature of a liquid slurry of coal particles.
  • the comminution of the silt, by mixture with these percentages of spent sulfite liquor permits the treated silt to move as coal fines through chutes and screens of handling apparatus without objectionable hold-up or coating or adhesion of the coal fines in the apparatus.
  • the following examples are illustrative of the processing of silt with the spent sulfite and are not limitative.
  • Coal fines or silt containing by weight of water, are mixed with 3% by weight of bindarene liquid at room temperature.
  • the mixing takes place in a cement mixer hopper in which the mixture is tossed on itself by a rotary motion of the hopper.
  • the mixing formed a number of small balls but did not form a heavy rubbery mass.
  • This example indicates that 3% by weight of spent sulfite liquor produces a satisfactory comminution of agglomerated coal dust containing 30% by weight of water.
  • EXAMPLE 11 Two and one-half percent bindarene flour is mixed with silt containing 15% by Weight of water to form small soft balls which break up readily under mechanical action. T 0 this was added another 15% of water, bringing the silt to a water content of 30%. This produced, by a tumbling action, small, irregular chunks of material which are not gummy and which remain dry so as not to stick to metal.
  • the products of this example are good for handling in ordinary silt handling apparatus and are satisfactory for the purposes of the product of this invention.
  • Tora B is m ed n a q a ty of 2??? y wei of silt containing 15% by weight of water to form a very soft product by tumble mixing.
  • the product contains a few balls and is dryer in its physical properties than the product of Example II with a 15 by weight of water silt. 15 of water with no Toranil B was added to the mixture thus bringing it up to 30% by weight of water by tumble mixing action. The mixing forms a dry mass of coal fines with small easily breakable lumps of coal fines.
  • EX P E V Marasp rs N so id is mi ed i a q a y of 2%% y weight with silt containing 15% by weight of water to orm a p oduct by tumble mixi g o loose material of appr ximately he o gina pa i i of the l fin h p du t cunta n ery ew sm ll p ec s f a a ed co fi her s no form tio of ub a Pieces f.
  • Goulac is tumble mixed with coal fines containing 15% by weight of Water to produce a comminuted coal fines product containing small lumps of rubber-like balls and some material which sticks to a metal container. Additional water is added to this mixture to bring it up to 30% by weight of water. It forms a dough-like material as a product which will stick slightly to a metal surface but can be broken into small lumps.
  • the products of this example are relatively satisfactory for the purpose of this invention. It is to be noted that Goulac is'a non-desugared spent sulfite compound.
  • Toranil A liquid is mixed with coal fines containing 15% by weight of water to produce a very flufiy and light product which does not produce small balls even with tumble mixing and which will not stick to metal.
  • EXAMPLE XI Fifty gallons of bindarene are mixed with 100 tons of agglomerated coal siltcontaining about 15% by weight of water and a substantial proportion of 200-mesh coal particles in cohesive layers. The substances are mixed in a mixer containing a series of paddles rotating on a horizontal axis within and counter to the action of a drum. The substances enter the drum below the tumbling mass and are thrown back on themselves. The resultant product contains comminutible lumps of coal fines.
  • EXAMPLE XII Three hundred and thirty pounds of bindarene liquid is mixed with 10 tons of agglomerated silt containing about 15% by weight of water and containing 200- mesh particles of coal in cohesive layers. The substances were mixed in the apparatus described in Example XI to produce a comminutible coal fines product.
  • EXAMPLE XIII One hundred pounds of-coal silt containing a substantial proportion of 200-mesh coal particles and 25% moisture is tumbled in a pelletizer barrel for 2 minutes and .10 seconds. During the time of tumbling the silt in the pelletizer is sprayed with 5 /2 ounces of spent sulfite liquor in a period of 1 minute to provide 34% by weight of the silt and 1.3% by weight of the moisture. The product of this example is not satisfactory for normal handling.
  • Table II of examples shows the procedure of Example XIII repeated with varying quantities of spent sulfite liquor in varying periods of time.
  • the rate of application of spent sulfite liquor is maintained at 5 /2 ounces per minute.
  • Example XIV-Silt sticks to barrel of pelletizer, lumps smaller, mixture not perfect.
  • Example XVSilt sticks to barrel less, mixture more satisfactory and uniform.
  • Example XVISilt sticks to barrel for the most part only slightly and has a loose formation.
  • a satisfactory comminutible product may be obtained by treating silt, including agglomerated layers of 200- mesh particles, With spent sulfite liquor in the proportion of 1 part by weight of spent sulfite liquor to 5 parts by weight of moisture in the silt.
  • spent sulfite liquor in the proportion of 1 part by weight of spent sulfite liquor to 5 parts by weight of moisture in the silt.
  • spent sulfite liquor it has been found preferable to use the spent sulfite liquor proportions up to 20% by weight of the moisture in the silt.
  • As little as .02% by weight of the spent sulfite liquor to the quantity of moisture in the silt has been found capable of providing the comminutible product of this invention from silt which includes agglomerated layers of 200-mesh particles.
  • the silt deposited as refuse from coal screening in the classification of coal sizes, contains a substantial proportion of coal fines of 200-mesh particles together with 10%v by weight of water. In many cases, such silt is made up of a major proportion of coal fines of 200- mesh containing 10% by weight of water.
  • the processing of such silt, according to this invention, with spent sulfite produces a product which will not cling to coal apparatus surfaces. It has been found that the agglomeration of the 200-mesh particles with the 10% by weight of water can be destroyed by the use of spent sulfite, according to this invention.
  • the specific amount of spent sulfite liquor or dry powder necessary to remove the agglomeration of the agglomerated silt varies according to the silt being treated.
  • the factors entering into the quantity of spent sulfite necessary are indicated above. Accordingly, in the operation of this invention, the percent of spent sulfite incorporated in the silt, particularly in the agglomerated 200-mesh particles varies within the defined range, according tothe presence of said abovementioned factors.
  • the treated silt preferably does not contain a percentage of Water that will make it soft in handling for shipment. If the silt contains excessive water, it becomes too sloppy to be used as a fuel and must be dehydrated. Accordingly, it is preferred that the treated silt contain not more than 15% water. However, this invention is applicable to treated silt containing up to 30% by weight of water. As the silt before treatment generally contains in the neighborhood of 15 by weight of water, the addition of up to 3% spent sulfite liquor does not seriously eifect the consistency of the treated silt.
  • silt containing as much as 40% by weight of water provides a usable but less desirable product when treated according to this invention.
  • Such silt when treated with up to 3% by weight of spent sulfite liquor, forms larger chunks of material than is obtained in the processing of silt containing lesser amounts of water.
  • this product is not one that is sought by this invention.
  • Water or moisture of the coal or silt as used herein refers to the moisture of the coal which is measured by the loss in weight obtained by drying the coal at a temperature between 104 and C. under standard conditions.
  • the spent sulfite may be introduced for, incorporar tion with the agglomerated silt in any manner which will produced the desired modification of. the agglomerating and adhesive characteristics of the silt particles and produce a relatively dry type of substance.
  • The. spent sulfite may be fed to the untreated silt by batch feeding into a simple rotary mixer, as indicated in; Examples I through X, above. It is. preferable, however, that the spentv sulfite liquor or solids. be introduced for incorporation by some atomizing or finely sub-dividing. means, such. as a spray nozzle. It has been determined that spraying spent sulfite liquor onuntreated silt. produces desired results with smaller amounts of spent sulfite material.
  • the agglomerated silt material provides a means for adjusting the ratio. between the materials. This ratio can then be adjusted to the requirements, as, indicated by the. moisture contentof. the agglomerated silt.
  • the spray nozzle capacity may be adjusted to provide an economic but adequate quantity of spent sulfite material.
  • agglomeration is employed herein to describe the massing of the coal silt and particularly the 20(:).-mesh particles, which massing or agglomeration is caused. by the adhesion between the silt particles.
  • This adhesion can be considered to. cause a more or less unified body or substance in which the particles are cohering objects.
  • Comminution is used to describe the action of the process in decreasing the adhesiveness between the particles.
  • the particles after they have been: treated are decreased in adhesiveness and are comminutible. or may be comminuted.
  • The. first product of the invention is to form the formerly cohesive particles, which make: up the agglomerated.
  • silt into balls, slivers, flakes or flocs of coal in which the particles have a decreased adhesiveness and are, therefore, comminutible;
  • These balls, slivers, flakes or fiocs form a dry mass of loose material. They. are easily breakable lumps and when; broken, readily form small particles andcan be. reduced to the original particle size.
  • the balls, slivers, flakes or fiocs made from -200-mesh silt, such as liver can be processed to form particles of 200-mesh.
  • Such. comminution is the full treatment of the process of this invention and produces the ultimate product. it will be understood, however, that this invention is. not limited to this complete treatment and that it involves the incomplete treatment of the preparation of the first product as well.
  • the agglomerated silt which is treated according to this invention, clings to metal surfaces so as not to be subject to the gravitational pull of its own weight.
  • the balls, slivers, flakes or fiocs will not cling to surfaces and will slide across ametal surface under a gravitational pull.
  • this invention applies to the processing of anthracite silt.
  • the invention can also be applied to the processing of bituminous silt, for example, itcan be used with buck dust which is otherwise valueless. for burning purposes.
  • the spent sulfite material is described as incorporated in silt containing aqueous moisture.
  • This invention is equally applicable to. the treatment ofag-glomerated silt containing other compositions of moisture.
  • two means for mechanically stirring or breaking up the agglomerated silt have been set forth.
  • additional: methods. and apparatus may be employed to effectuate the process of this inventionv and to achieve the desired: product.
  • Such modifications may vary the amount of spentv sulfite material required and its ratio to the silt moisture content.
  • invention which relates to the treatment of' agglomerated coal silt containing substantial quan tities of 200-mesh particles and from which excess water has been drained. off.
  • characteristics ofthe silt enter into. the attainment of the desired comminution. These characteristics. include the siltmoisture content; the fineness of the silt particles, the source process from which the silt originates or the agent used' in. separating sizes below buckwheat #4 and 5. Another characteristic. is the hardness of the anthracite from which the agglomerated silt is derived,.w hich hardness is a, product of the veins and locations from which the silt is derived. All of these characteristicscombine to. produce an untreated silt which is agglomerated and the treatment of this process reduces the adhesivenessof the siltparticles.
  • the advantages of this invention can. be seen in considering the silt asa fuel.
  • The. silt largely passes through a %2-1I16Sh screen. It is formed. into a silt bank which retains a large percentage of the processing water.
  • the silt in the physical form that it assumes. inthe silt bank cannot be successfully used as a fiuel at the present time because'of the diflicultyin handling. the material.
  • siltbanksiare-fines which, it below ZOO-mesh, cake heavily; it will not dump out of railroad cars; it will not loosenv itselfon shaker screens; it forms a solid coating over the mesh of shaker screens and thus vitiates the separating purpose of the shakers; and it packs in bins and in feed pipes.
  • This invention by its process has produced a product which. completely avoids. and obviates the above disadvantages of the silt-
  • the products of the above noted examples are derived from the moisture retaining silt and may be handled and processed in the normal manner of anhydrous or relatively dry coal having particle size of the order of coal fines, as identified above.
  • Another advantage of this invention isthe production of a silt having dry properties without the use of heating or grinding.
  • a product is formed which may be blown in powder form into the furnaces with available equipment by standard proceduresafter passing through a combined ball and heating mill for further reduction in sizes.
  • the product is comminuted coal fines or has the properties of comminuted coal fines and the process produces this product from an; agglomerated silt material which includes silt bank liver.
  • the product of this invention does not form particles which are easily airborne and are not susceptible to movement by gusts of wind. This facilitates transportation and obviates the necessity of preventing blowing of the silt out of railroad cars during transit.
  • a process of producing non-adherent disintegrated coal fines from coal silt containing. adherent -200 mesh particles which comprises treating an agglomerated compact adhesive coal silt containing a substantial proportion of 200 mesh particles and from to 30% of water by weight of the silt, incorporating with said silt a composition selected from the group consisting of spent sulfite liquor and the powdered solid form of sulfite liquor, said composition containing solids of spent sulfite liquor in a proportion of about .1% to 3% by weight of the silt, and mixing the composition and the coal silt into a mixture containing less than 30% of water by weight of the silt and until the coal silt is breakable by mechanical action.
  • a process of producing non-adherent coal fines from waste coal silt containing adherent -200 mesh particles which comprises treating agglomerated compact adhesive coal silt containing a substantial proportion of 200 mesh particles and from 10% to 30% of water by weight of the silt, incorporating with said silt from about .02% to 20% of spent sulfite liquor by weight of the water content of the silt, said spent sulfite liquor being a product from paper processing and containing not more than 50% water by weight and mixing the spent sulfite liquor and the coal silt into a mixture containing not'more than 30% by weight of water and until the coal silt is breakable by mechanical action.
  • a process of producing non-adherent disintegrated coal fines from waste coal silt containing adherent 200 mesh particles which comprises treating an agglomerated compact adhesive coal silt containing a substantial proportion of -200 mesh particles and from 10% to 30% of water by weight of the silt, incorporating with said silt from about .1% to 3% by weight of the silt of the powdered solid form of spent sulfite liquor from paper processing and mixing the powdered solid form of spent sulfite liquor and coal silt to a mixture containing not more than 30% of water by weight of the silt and until the coal silt is breakable by mechanical action.
  • a process of producing non-adherent disintegrated coal fines firom waste coal silt containing adherent --200 mesh particles which comprises treating an agglomerated compact adhesive coal silt containing a substantial proportion of 200 mesh particles and from 10% to 30% of water by weight of the silt, incorporating with said silt from about .2% to 6% of spent sulfite liquor by weight of the silt, said spent sulfite liquor being from paper processing and containing not more than Water by weight of the liquor, and mixing the spent sulfite liquor and the coal silt to a mixture containing not more than 30% of water by weight of the silt and until the coal silt has been disintegrated and rendered nonadhesive.
  • a method of forming a non-sticky, dry flowable coal dust having a substantial portion of particles of less than 200 mesh from sticky waste coal silt which comprises treating an agglomerated compact adhesive waste coal silt containing a substantial portion of 200 mesh particles and from 10% to 30% of water by weight of the silt, incorporating with said silt a composition selected from the group consisting of spent sulfite liquor containing not more than 50% of water by weight of the liquor and the powdered solid form of spent sulfite liquor in a proportion of from 0.2% to 6% of said spent sulfite liquor by weight of the silt and from 0.1% to 3% of said powdered solid form by weight of the silt to provide friability and pulverulence to said agglomerated silt and mixing said spent sulfite composition in said silt to cause the disintegration of said silt.
  • Disintegrated non-adhesive waste coal silt comprising particles of silt ranging from 20 mesh particles to 400 mesh particles having from 10% to 30% of water by weight of the silt, said silt having spent sulfite liquor containing not more than 50% of water by weight of the liquor in the proportion of from about .2% to 6% by weight of said silt.
  • Disintegrated non-adhesive waste coal silt comprising particles of silt ranging from 20 mesh particles to 400 mesh particles having from 10% to 30% of water by weight of the silt, said silt having the solids of spent sulfite liquor in the proportion of from about .1% to 3% by weight of said silt.

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Description

nited States Patent C) COMMINUTED COAL FINESHAND METHOD on 5 COMMINUTING AGGLOMERATED COAL FINES Waldemar Hartmann, Mountain Lakes, N. J.
No Drawing. Application July 7, 1955, Serial No. 520,631
7 Claims. (01. 44-16 This invention relates to the processing of agglomerated coal fines and, more particularly, to the treatment of agglomerated coal fines with spent sulfite liquor.
Silt is the final product resulting from the processing of coal, for example, anthracite silt comes from the preparation of run-of-mine anthracite. This run-of-mine coal is processed through a coal breaker in which it passes over a bull shaker. The bull shaker segregates the larger lumps of coal and sends them through crushing operations to a reduction in size. The crushed coal, together with the segregated run-of-mine coal, are then fed to a set of shaker screens which classify the lumps of coal according,
to size in the well known sizes of egg, stove, nut, pea, buckwheat, rice and barley. This screening produces buckwheat #4 which will pass through a screen having mesh openings of of an inch and will pass over a screen having mesh openings of of aninch. Further screening of the material that passes through mesh openings of of an inch produces buckwheat #5 which are pieces of coal that pass through a screen having openings of 7 of an inch and over a screen having openings of of an inch. The remaining coal is known as anthralarger particle size.
cite silt. The anthracite silt contains particles in the following range of sizes:
+20-mesh particles which pass over a 20-mesh screen +40-mesh particles which pass over a 40-mesh screen +80-mesh particles which pass over an SO-mesh screen +100-mesh particles which pass over a l00-mesh screen i-ISO-mesh particles which pass over a lSO-mesh screen +200-mesh particles which pass over a'ZOO-mesh screen --200-mesh particles which pass through a 200-mesh screen The anthracite silt is discarded from the classification procedures and piled up in the form of huge banks or dumped into abandoned stripping pits. In addition to the general accumulation of the various particle sizes of the silt during the normal classification process, a concentration of the ZOO-mesh silt occurs mostly at the end of a period of breaker operation, such as after a shift or a days run. The ZOO-mesh particles are so fine in body that a normal breaker operation will tend to accumulate them in various settling tanks and traps provided for that purpose. At the end of the period of operation, this accumulation is removed by flushing the surfaces with a sluice of water through the breaker equipment. This sluice of water carries the ZOO-mesh particles into the culm bank in which the silt is accumulated. The fine coal of the ZOil-mesh particles is deposited in a layer, as a result of this flushing of the material. This layer of almost exclusively 200-mesh particles and the water which it retains at the end of the flushing reaction, is referred to as liver. The silt bank .on which the silt is accumulated thus contains a range of co-particle sizes with interspersed concentrations of ZOO-mesh particles in layers. These layers of the concentrated --200-mesh particles contain a tenacious adhesiveness and stubbornly resist eomminution. The variety of partielesizes in the silt is a product of factors in the operation of the classification, such as the stage of the operation during which the silt is deposited.
As indicated by the description of the deposition of the liver layers in the silt, the coal dust from the classification operation is carried to the silt bank by a liquid medium, such as water. This liquid medium carries the silt particles by floatation and most of the liquid drains off the silt bank leaving the coal particles as a deposition.
Some of the moisture of the floatation medium is retained in the silt bank after deposition. This retained moisture and other factors cause the coal fines of the silt to become agglomerated into a mass of material which does not exhibit the properties of free flowing comminuted particles. The ZOO-mesh particles are agglomerated by adhesion so badly after collection in a silt bank that the coal cannot be processed. It will not dump out of cars, it forms a solid coating over the mesh of shaker screens and it coats or packs in bins and in feed pipes. The +200-mesh particles and larger particles also exhibit these properties to some degree. The -200-mesh particles form a substance which is impossible to handle by ordinary means even when mixed with coal fines of a Accordingly, quantities of fines and particularly coal fines having particles of ZOD-mesh cannot beprocessed for combustion economically. f
It is an object of this invention to provide comminuted coal fines of a particle size which will substantially pass a ZOO-mesh screen.
It is another object of this invention to provide comminuted coal fines from agglomerated silt which will handle in ordinary coal fines handling apparatus.
It is still another object of this invention to provide coal fines from agglomerated coal fines of a silt bank which will pass a screen of ZOO-mesh.
Another object of this invention is to provide a method of decreasing adhesiveness in agglomerated fine particles of coal.
A still further object of this invention is to provide a means and method for decreasing adhesiveness in agglomerated particles which have had an original size of passing through a fl -mesh screen.
It is still another object of this invention to provide a means and method for providing comminntible coal fines from agglomerated coal silt containing a substantial proportion of water, such as up to 30% water.
These and other objects of this invention will become more apparent upon consideration of the following description.
In general, this invention provides treating agglomerated fines of a size that will pass a of an inch screen aperture and produce .a comminutible product from said agglomerated fine coal silt which can be handled in normal coal silt handling equipment. The comminutibility is effected at least in part by a decrease of the adhesiveness of the ZOO-mesh particles. This comminution is achieved by mixing the agglomerated coal silt with a small percentage of spent sulfite.
Spent sulfite is a compound which is made up principally of calcium lignosulfonate. It also may contain sodium lignosulfonate in a substantial proportion, together with certain sugar degradation products. Stated otherwise, it may be considered for the purpose of this description that spent sulfite in general refers to the complex mixture of the salts of low molecular weight of lignosulfonic acids and the alkaline hydrolysis products of pentoses and hexoses which are extracted from coniferous woods in the sulfite pulping process. The spent sulfite liquor also contains tannin and ash in appreciable percentages.
The Journal of Technical Association of the Pulp and Paper Industry, at page 555, indicates that calcium solids, while the sugar products make up about 20% of the total spent sulfite solids. Also included in the spent Typical chemical analysis of bindarene flour Solids basis: Average, percent sulfite may be calcium and magnesium oxides, sulfite 3:9 as S04 and other substances which make up the re- 5 z -1a mainder of the spent sulfite solids. The spent sulfite i e liquor is a solution of the spent sulfite solidsin water. ig e The liquor is about half water by weight. The specific 9 spent sulfite compounds referred to herein are defined Ca mum OX1 e as to composition in greater detail below. 10 Iron The spent sulfite liquor contains 24% free S02, g/lzfnesmmfioxl e 24% so.., 2-5% sot: 80-90% solids and 12-16% 0 0X1 e 03 ash with calcium compounds, carbohydrates anddignone Characteristics of Tomnil A sulfonate. Spent sulfite is commercially available in llquld and powdered form in the products of several companies. 15 Cofiee colored viscous liquid 4 The following Table I sets forth the products available Specific gravity (60 F./60 F.), 1.24 as identified by their trademark names and associated Baum, 28.5 with the supplying companies.
TABLE I Name liq- Name solid Name liq- Name solid Lbs. per Company uid sugar sugar retained uid dedesugared gallon retained sugared International Paper Company-.. Bindarene Bindarene Flour .L.-. 10. 04
Marasperse 0. Marathon Corp Norlig igi 10.08
Maraboud Lake States Yeast Corp 10.05 Robeson Process 00 10.08 American Gum Products Oompony.
All of these compounds contain the waste spent sulfite.
The following are the analyses of the chemical compositions and characteristics of the spent sulfite compounds, set forth in Table I, as identified by the trademark names listed therein:
Characteristics of bindarene liquid Brown viscous liquid Completely miscible in water 50% Water solution Specific gravity 1.26 Baum) pH 5.5
Viscosity, 175 centipoises 20 C. (60 R. P. M. Brookfield) Boiling point, 212 F.
Freezing point, 17 F.
Heat value, 3900 B. t. u.s
Sugar content, 20% of solids Calcium lignosulfonate, 70% of solids Inorganic material, 10% of solids Typical chemical analysis of bindarene liquid Solids basis: Average, percent Volatile acids 3.9 Total sulfur 4.1 Free sulfur dioxide 0.2 Sulfur trioxide 0.8 Sulfone S02 6.6 Calcium oxide 4.3
Iron 0.02 Magnesium oxide 1.9 Sodium oxide 0.3
Characteristics of bindarene flour Light yellow powder Particle size, 95% thru 100 mesh screen Completely soluble in water Moisture content, 5%
Organic material, 90%
Inorganic material, 10%
Sugars 20% (mannose, glucose, xylose, etc.) Calcium lignosulfonate, 70%
Heat value, 7800 B. t. u.s
Viscosity (cps.):
70 C.-- C.--13O '30" C.-420 pH (50% water solution), 4.5 to 4.6 Boiling range, 107 C. to 108 C. Freezing range, -4 C. to -6 C. Surface tension (dynes/cm.) (10% water solution), 48
Characteristics 0] Torarzil B Free flowing light tan powder Apparent bulking value 1 (#/ft.
Loose 25-29 Tamped 35-39 Equilibrium moisture 2 7.7 pH (50% Water solution) 4.6 to 4.7
Surface tension (dynes/cm.) (10% Water solution) 48 Charring temp:
In air (30 min.) C 475 (Approx. 1 min.) C 600 In nitrogen (30 min.) C 500 (Approx. l min.) 23C 630 1 Modification of ASTM C2942. 2 Percent increase in weight when oven dry material is exposed at 70 F. and 50% R. H.
Typical chemical analysis of Toram'l dry solids arrears Typical chemical analysis of Ga'ulac Water percent" 1.29 Ash i do 11.89 Iron do .022 Calcium made (10"-- 4.59 Magnesium oxide do 2.75 Solids do. 98.71 pH 6.73
Typical chemical analysis of Glutrin [Baum 31.00 60.] Water percent 48.75 Ash do 5.82 Iron do .011 Calcium ox do 2.52 Magnesium oxide do 1.35 Solids dn 51.25 pH 6.90
Typical chemical analysis of Marabond Percent CaSO4- /2H2O i 0.68 CaSO3'H2O 2.63 F6203 0.05 A1203 0.16 SiOz 0.28 Sulfonic SOs 10.25 Sulfonic Ca i 2.56 CaCOz 2.41 CaO over 7 7.58 MgO 0.26
Inorganics 26.86
Organics 73.14 Calcium 'lignosulfonate 77.98
Typical chemical analysis of Marasperse C Moisture 7.00% maximum. 40 pH3% solution 6.7-7.3. Total sulfur (as S) 4.97% on moisure free basis. Sulfate sulfur (as S) 0.25% on moisture free basis. Sulfite sulfur (as S) None. CaO 3.83% on moisure free basis. 4 MgO 0.39% on moisture free basis. NazOa 3.50% on moisture free basis. FezOa 0.17% on moisture free basis. Reducing sugars None. OCH3 9.74% on moisture free basis.
Composition (on moisture free basis) Calcium lignosulfonate, percent:
Lignin 67.4 503 11.8 Ca, Na, Mg 2.8
82.0 Organics, nonligneous, percent 14.2 lnorganics, percent:
casot-i znzo 1.13 Fe 0.11 Na over sulfonic 2.60
Typical chemical analysis of Marasperse N Moisture 6.00% maximum. pH3% solution 7.07.5. Total sulfur (as S) 6.10% on moisture free basis. Sulfate sulfur (as S) 1.62% on moisture free basis. Sulfite sulfur (as S) 0.03% on moisture free basis. CaO 0.50% on moisture free basis. MgO 0.46% on moisture free basis. NazO Q 9.32% on moisture free basis. 1
All of the products set forth in the above Table I may be employed in the process of this invention and produce the comminutible fines product in varying degrees of comminution or free flowing properties. Spent sulfite liquor obtained from the pulping of wood contains sulphur oxides, calcium compounds and carbohydrates, as indicated above. Some of the spent sulfite compounds have been desugared to reduce the percentage of sugars in the spent sulfite liquor. T oranil A and T oranil B, set forth in Table I, are desugared compounds having a low carbohydrate content. The spent sulfite liquor is made up of about 51% solids and 49% water. As indicated in Table I, the spent sulfite liquor is also available in powdered solid form, with or without its sugar content. An analysis of the lignon complex groups of some spent sulfite liquors is indicated by the following chemical composition:
Carbon percent 50.22 to 56.27 Hydrogen do 5.22 to 5.87 Sulfur do 5.52 to 8.80
This invention provides for a processing of silt which changes the silt from a tenaciously adhering agglomeration of the particles into a material which is either in comminuted form, or is comminutible having decreased adhesiveness. The original agglomerated silt is in a physical condition which prevents it from passing through normal classifying shaker or vibrator screens. It also is a material which will cling to the walls and surfaces of a retaining receptacle and resist or defy removal. Such properties of silt render it prohibitively difficult to han dle. According to this invention, these properties of the agglomerated silt may be counteracted by a mixing of spent sulfite in the agglomerated material. This mixing or other incorporation of the spent sulfite in the agglomerated material removes the objectionable properties and allows the silt to become a substance which can be processed for further use, such as combustion.
It has been found that the amount of spent sulfite compound, which must be mixed or otherwise incorporated with the agglomerated silt, is related to the percentage of moisture in the silt. The percentage of spent sulfite is also dependent upon the average fineness of the silt and the procedure used in the separation of the silt from the other coal.
The flotation process of separating the coal particles may use instead of water such liquids as fuel oil, pine oil, alcohol or kerosene in separating sizes below buckwheat #4 and #5. The use of such flotation media influences the amount of spent sulfite necessary to bring about a comminution of the silt resulting from said previous separation by flotation. Similarly, the average fineness of the particles in the silt is determinative of the amount of spent sulfite necessary in bringing about satisfactory comminutibility in that as a rule the finer the particles in the silt, the greater the amount of spent sulfite necessary to produce comminutibility.
The liquid content of the silt material is closely corre lated to the relative amount of spent sulfite needed. It has been deprmined, when the comminuting material i mad up of rZOQ mesh Pa t cle in a glomerated sendition, that spent sulfite liquor in a ran e 9f from 0.2% to 20% of the water content of the silt will produge the comminuting eifect of this invention. A silt containing a substantial proportion of -200-mesh particles and not less than 10% by weight of water when treated with from 002% to 2% of spent sulfite liquor will lose its property of clinging to surfaces of coal handling equip ment.
This process may be used for treating silt containing up to 30% by weight of water. With 30% by weight of water, the percent of spent sulfite liquor ranges from 006% to 6% by weight of the silt treated. The silt containing these percentages of water, when treated with the respective percentages of spent sulfite liquor will result in a product which forms easily breakable lumps and has lost the objectionable adhesiveness, so as to not stick to metal surfaces. Larger percentages of the spent sulfite liquor will result in a product which is sloppy and which contains an excess of moisture. The product Will not be comminuted particles, having a relatively dry nature, but will be more in the nature of a liquid slurry of coal particles.
The comminution of the silt, by mixture with these percentages of spent sulfite liquor permits the treated silt to move as coal fines through chutes and screens of handling apparatus without objectionable hold-up or coating or adhesion of the coal fines in the apparatus. The following examples are illustrative of the processing of silt with the spent sulfite and are not limitative.
EXAMPLE I Coal fines or silt, containing by weight of water, are mixed with 3% by weight of bindarene liquid at room temperature. The mixing takes place in a cement mixer hopper in which the mixture is tossed on itself by a rotary motion of the hopper. The mixing formed a number of small balls but did not form a heavy rubbery mass.
A mixture of an equivalent amount of bindarene liquid in silt, containing by weight of water, formed a soggy mass which would not stick to metal and could be broken up by mechanical action. This example indicates that 3% by weight of spent sulfite liquor produces a satisfactory comminution of agglomerated coal dust containing 30% by weight of water.
EXAMPLE 11 Two and one-half percent bindarene flour is mixed with silt containing 15% by Weight of water to form small soft balls which break up readily under mechanical action. T 0 this was added another 15% of water, bringing the silt to a water content of 30%. This produced, by a tumbling action, small, irregular chunks of material which are not gummy and which remain dry so as not to stick to metal. The products of this example are good for handling in ordinary silt handling apparatus and are satisfactory for the purposes of the product of this invention.
EXAMPLE III Tora B is m ed n a q a ty of 2??? y wei of silt containing 15% by weight of water to form a very soft product by tumble mixing. The product contains a few balls and is dryer in its physical properties than the product of Example II with a 15 by weight of water silt. 15 of water with no Toranil B was added to the mixture thus bringing it up to 30% by weight of water by tumble mixing action. The mixing forms a dry mass of coal fines with small easily breakable lumps of coal fines.
The products of this example are highly satisfactory, both with the 15% and 30% by weight of water samples of silt.
EXAMPLE IV Two and one-half percent of Marabond spent sulfite is mixed h silt remainin 15% by we ht o water in a tumble mixing action to form a fiufiy product containing lumps which crush easily. This material has no binding properties at all and can be easily stirred indicating a highly comminuted physical state. Additional water was added without changing the Marabond percentage, bringing the silt up to 30% by weight of water to produce a product which does not form permanent chunks or balls. The resultant products of this example are highly satisfactory for the purposes of this invention.
EX P E V Marasp rs N so id is mi ed i a q a y of 2%% y weight with silt containing 15% by weight of water to orm a p oduct by tumble mixi g o loose material of appr ximately he o gina pa i i of the l fin h p du t cunta n ery ew sm ll p ec s f a a ed co fi her s no form tio of ub a Pieces f. teri l in th p odust- Add ion w r i added to bring the mixture up to 30% by weight but no Marasperse N is added. This produces a comminutible product by tumble mixing which is slightly more adhesive than treated coal fines with 15% by weight of water. The resultant product has a putty-like appearance. The products of this example may be handled in coal handling apparatus.
EXAMPLE V I Two and one-half percent of Marasperse C is mixed with coal fines containing 15% by weight of water to form a powdered product containing a few scattered lumps of agglomerated material. This product is satisfactory for the purposes of this invention.
EXAMPLE VII Two and one-half percent by weight of Maracarb NC is mixed with coal fines containing 15% by weight of water by a tumbling action to produce a dry product of comminuted coal particles containing little balls. The small balls are formed by the tumbling action of the mixing motion. The balls break up easily. To the above was added suflicient water to make a 30% mixture without adding Maracarb NC. This mixture formed a comminuted coal fines product having dry small balls which break up easily under mechanical action to form a completely comminuted product, The products of this example are satisfactorily dry and comminuted for handling in a coal handling apparatus.
Two and one-half percent of Goulac is tumble mixed with coal fines containing 15% by weight of Water to produce a comminuted coal fines product containing small lumps of rubber-like balls and some material which sticks to a metal container. Additional water is added to this mixture to bring it up to 30% by weight of water. It forms a dough-like material as a product which will stick slightly to a metal surface but can be broken into small lumps. The products of this example are relatively satisfactory for the purpose of this invention. It is to be noted that Goulac is'a non-desugared spent sulfite compound.
EX M LE. I
Two and one-half percent of Toranil A liquid is mixed with coal fines containing 15% by weight of water to produce a very flufiy and light product which does not produce small balls even with tumble mixing and which will not stick to metal.
EXALIPLE X Two and one-half percent by weight of Norlig is mixed with coal fines containing 15% by weight of water to form a cornrni uted non-sticky product after thorough stirring and mixing, Small lumps are formed but may be readily broken up. The coal fines particles of the coal silt in the above examples all have an original particle amt-1s screen.
The desugared spent sulfite produces a comminuted product which is less subject to hygroscopic action than the comminuted coal fines produced with non-desugared 5 spent sulfite. This non-hygroscopic property of the comminuted coal sent through the pelletizer produces a flufiy product of the comminuted coal fines and is not subject to atmospheric moisture. The products made from Marabond, Marabond 'N and Marasperse C are less hygroscopic than the products made by treatment with Goulac and Marasperse NC.
In Examples I through X, the mixing of the spent sulfite in the silt material is accomplished by the rotating of the substances in a cement mixer. To some extent, this 5 type of mixing produced balls of silt material which mixed with the spent sulfite mainly through a'covering on the outside of the balls which did not penetrate. 'Accordingly, the mixing is not as eflicient as can be obtained with other forms of mixing apparatus.
EXAMPLE XI Fifty gallons of bindarene are mixed with 100 tons of agglomerated coal siltcontaining about 15% by weight of water and a substantial proportion of 200-mesh coal particles in cohesive layers. The substances are mixed in a mixer containing a series of paddles rotating on a horizontal axis within and counter to the action of a drum. The substances enter the drum below the tumbling mass and are thrown back on themselves. The resultant product contains comminutible lumps of coal fines.
EXAMPLE XII Three hundred and thirty pounds of bindarene liquid is mixed with 10 tons of agglomerated silt containing about 15% by weight of water and containing 200- mesh particles of coal in cohesive layers. The substances were mixed in the apparatus described in Example XI to produce a comminutible coal fines product.
The following examples are presented as illustrating the efiiciency and advantage provided this invention by processing the silt in a pelletizer and spraying the spent sulfite on the silt under pressure through a nozzle. It will be understood that these examples of the means of processing according to this invention are not limitative on its scope.
EXAMPLE XIII One hundred pounds of-coal silt containing a substantial proportion of 200-mesh coal particles and 25% moisture is tumbled in a pelletizer barrel for 2 minutes and .10 seconds. During the time of tumbling the silt in the pelletizer is sprayed with 5 /2 ounces of spent sulfite liquor in a period of 1 minute to provide 34% by weight of the silt and 1.3% by weight of the moisture. The product of this example is not satisfactory for normal handling.
The following Table II of examples shows the procedure of Example XIII repeated with varying quantities of spent sulfite liquor in varying periods of time. The rate of application of spent sulfite liquor is maintained at 5 /2 ounces per minute.
A summary of the results is as follows: i T
Example XIV-Silt sticks to barrel of pelletizer, lumps smaller, mixture not perfect.
Example XVSilt sticks to barrel less, mixture more satisfactory and uniform.
Example XVISilt sticks to barrel for the most part only slightly and has a loose formation.
A satisfactory comminutible product may be obtained by treating silt, including agglomerated layers of 200- mesh particles, With spent sulfite liquor in the proportion of 1 part by weight of spent sulfite liquor to 5 parts by weight of moisture in the silt. In other words, when using spent sulfite liquor, it has been found preferable to use the spent sulfite liquor proportions up to 20% by weight of the moisture in the silt. As little as .02% by weight of the spent sulfite liquor to the quantity of moisture in the silt has been found capable of providing the comminutible product of this invention from silt which includes agglomerated layers of 200-mesh particles.
The silt, deposited as refuse from coal screening in the classification of coal sizes, contains a substantial proportion of coal fines of 200-mesh particles together with 10%v by weight of water. In many cases, such silt is made up of a major proportion of coal fines of 200- mesh containing 10% by weight of water. The processing of such silt, according to this invention, with spent sulfite produces a product which will not cling to coal apparatus surfaces. It has been found that the agglomeration of the 200-mesh particles with the 10% by weight of water can be destroyed by the use of spent sulfite, according to this invention.
As pointed out above, the specific amount of spent sulfite liquor or dry powder necessary to remove the agglomeration of the agglomerated silt varies according to the silt being treated. The factors entering into the quantity of spent sulfite necessary are indicated above. Accordingly, in the operation of this invention, the percent of spent sulfite incorporated in the silt, particularly in the agglomerated 200-mesh particles varies within the defined range, according tothe presence of said abovementioned factors.
The treated silt preferably does not contain a percentage of Water that will make it soft in handling for shipment. If the silt contains excessive water, it becomes too sloppy to be used as a fuel and must be dehydrated. Accordingly, it is preferred that the treated silt contain not more than 15% water. However, this invention is applicable to treated silt containing up to 30% by weight of water. As the silt before treatment generally contains in the neighborhood of 15 by weight of water, the addition of up to 3% spent sulfite liquor does not seriously eifect the consistency of the treated silt. Although larger amounts of water inthis treated silt produce some of the above-noted undesirable properties, silt containing as much as 40% by weight of water provides a usable but less desirable product when treated according to this invention. Such silt, when treated with up to 3% by weight of spent sulfite liquor, forms larger chunks of material than is obtained in the processing of silt containing lesser amounts of water. As will be explained in greater detail below, this product is not one that is sought by this invention. a
Water or moisture of the coal or silt as used herein refers to the moisture of the coal which is measured by the loss in weight obtained by drying the coal at a temperature between 104 and C. under standard conditions.
It will be seen that if it is assumed the normal percentage of moisture in the untreated silt is approximately 15% by weight, that 3% by weight of the spent sulfite liquor provides the 5:1 ratio between silt moisture and the spent sulfite liquor, which is indicated as being a maximum preferred ratio. The critical limitation on the amount of spent sulfite is found to be in the minimum away-1s 11 amount. The: spent; sulfite: liquor must be at least .02% by weight of the silt, moisture.
The spent sulfite may be introduced for, incorporar tion with the agglomerated silt in any manner which will produced the desired modification of. the agglomerating and adhesive characteristics of the silt particles and produce a relatively dry type of substance. The. spent sulfitemay be fed to the untreated silt by batch feeding into a simple rotary mixer, as indicated in; Examples I through X, above. It is. preferable, however, that the spentv sulfite liquor or solids. be introduced for incorporation by some atomizing or finely sub-dividing. means, such. as a spray nozzle. It has been determined that spraying spent sulfite liquor onuntreated silt. produces desired results with smaller amounts of spent sulfite material. Similarly, it has, been determined that mechanically turning and breaking up the untreated silt material, Prior to and during the incorporation of the spent sulfite. material, provides superior results with lesser amounts-of the spent sulfite compounds. It thus will be seen that the manner of incorporation of; the spent. sulfite compounds in the agglomerated silt acts-as a factor in determining the amount or material necessary to achieve a satisfactory comminution of the agglomerated material.
It is a feature of this invention that by spraying the spent sulfite material onto. the agglomerated silt material provides a means for adjusting the ratio. between the materials. This ratio can then be adjusted to the requirements, as, indicated by the. moisture contentof. the agglomerated silt. Thus, by check testing the moisture of the agglomerated silt, the spray nozzle capacity may be adjusted to provide an economic but adequate quantity of spent sulfite material.
As indicated by the. above description, the use oi the term agglomeration is employed herein to describe the massing of the coal silt and particularly the 20(:).-mesh particles, which massing or agglomeration is caused. by the adhesion between the silt particles. This adhesion can be considered to. cause a more or less unified body or substance in which the particles are cohering objects. Comminution is used to describe the action of the process in decreasing the adhesiveness between the particles. Thus, the particles after they have been: treated are decreased in adhesiveness and are comminutible. or may be comminuted. The. first product of the invention is to form the formerly cohesive particles, which make: up the agglomerated. silt, into balls, slivers, flakes or flocs of coal in which the particles have a decreased adhesiveness and are, therefore, comminutible; These balls, slivers, flakes or fiocs form a dry mass of loose material. They. are easily breakable lumps and when; broken, readily form small particles andcan be. reduced to the original particle size. Thus, the balls, slivers, flakes or fiocs made from -200-mesh silt, such as liver, can be processed to form particles of 200-mesh. Such. comminution is the full treatment of the process of this invention and produces the ultimate product. it will be understood, however, that this invention is. not limited to this complete treatment and that it involves the incomplete treatment of the preparation of the first product as well.
As described above, the agglomerated silt, which is treated according to this invention, clings to metal surfaces so as not to be subject to the gravitational pull of its own weight. The balls, slivers, flakes or fiocs will not cling to surfaces and will slide across ametal surface under a gravitational pull.
Variousmodifications of this invention are. possible within its broad concept. First, it hasbeen stated above that this invention applies to the processing of anthracite silt. The invention can also be applied to the processing of bituminous silt, for example, itcan be used with buck dust which is otherwise valueless. for burning purposes.
A5, described in the examples herein, the spent sulfite material is described as incorporated in silt containing aqueous moisture. This invention is equally applicable to. the treatment ofag-glomerated silt containing other compositions of moisture. Also, two means for mechanically stirring or breaking up the agglomerated silt have been set forth. It will be understood that additional: methods. and apparatus may be employed to effectuate the process of this inventionv and to achieve the desired: product. Such modifications may vary the amount of spentv sulfite material required and its ratio to the silt moisture content. However, such variation from these modifications will not depart from the basic concept of this. invention which relates to the treatment of' agglomerated coal silt containing substantial quan tities of 200-mesh particles and from which excess water has been drained. off.
in. the. above description,.reference has been made to spent sulfite compounds, asidentified by trademark names and typical analyses 0t the spent sulfite compounds of these trade-marked compounds. It will be understood that other similar products may be employed in this invention.
As mentioned above, characteristics ofthe silt enter into. the attainment of the desired comminution. These characteristics. include the siltmoisture content; the fineness of the silt particles, the source process from which the silt originates or the agent used' in. separating sizes below buckwheat #4 and 5. Another characteristic. is the hardness of the anthracite from which the agglomerated silt is derived,.w hich hardness is a, product of the veins and locations from which the silt is derived. All of these characteristicscombine to. produce an untreated silt which is agglomerated and the treatment of this process reduces the adhesivenessof the siltparticles.
The advantages of this invention; can. be seen in considering the silt asa fuel. The. silt largely passes through a %2-1I16Sh screen. It is formed. into a silt bank which retains a large percentage of the processing water. The silt in the physical form that it assumes. inthe silt bank cannot be successfully used as a fiuel at the present time because'of the diflicultyin handling. the material. The base of the siltbanksiare-fines, which, it below ZOO-mesh, cake heavily; it will not dump out of railroad cars; it will not loosenv itselfon shaker screens; it forms a solid coating over the mesh of shaker screens and thus vitiates the separating purpose of the shakers; and it packs in bins and in feed pipes. These ditliculties are experienced even when coal particles, having. an original size greater than ZOO-mesh, make up the silt due to the particular kind of flotation process which has been used.
This invention by its process has produced a product which. completely avoids. and obviates the above disadvantages of the silt- The products of the above noted examples are derived from the moisture retaining silt and may be handled and processed in the normal manner of anhydrous or relatively dry coal having particle size of the order of coal fines, as identified above. I
Another advantage of this invention isthe production of a silt having dry properties without the use of heating or grinding. A product is formed which may be blown in powder form into the furnaces with available equipment by standard proceduresafter passing through a combined ball and heating mill for further reduction in sizes. The product is comminuted coal fines or has the properties of comminuted coal fines and the process produces this product from an; agglomerated silt material which includes silt bank liver. The product of this invention does not form particles which are easily airborne and are not susceptible to movement by gusts of wind. This facilitates transportation and obviates the necessity of preventing blowing of the silt out of railroad cars during transit.
In the abovedescription, illustrative embodiments have been set forth. by way of explanation. It will be understood that modifications of the specific procedures and percentages may be made in accordance with the spirit of the invention set forth herein. Accordingly, it is intended that this invention be limited only by the scope of the appended claims.
I claim:
1. A process of producing non-adherent disintegrated coal fines from coal silt containing. adherent -200 mesh particles, which comprises treating an agglomerated compact adhesive coal silt containing a substantial proportion of 200 mesh particles and from to 30% of water by weight of the silt, incorporating with said silt a composition selected from the group consisting of spent sulfite liquor and the powdered solid form of sulfite liquor, said composition containing solids of spent sulfite liquor in a proportion of about .1% to 3% by weight of the silt, and mixing the composition and the coal silt into a mixture containing less than 30% of water by weight of the silt and until the coal silt is breakable by mechanical action.
2. A process of producing non-adherent coal fines from waste coal silt containing adherent -200 mesh particles, which comprises treating agglomerated compact adhesive coal silt containing a substantial proportion of 200 mesh particles and from 10% to 30% of water by weight of the silt, incorporating with said silt from about .02% to 20% of spent sulfite liquor by weight of the water content of the silt, said spent sulfite liquor being a product from paper processing and containing not more than 50% water by weight and mixing the spent sulfite liquor and the coal silt into a mixture containing not'more than 30% by weight of water and until the coal silt is breakable by mechanical action.
3. A process of producing non-adherent disintegrated coal fines from waste coal silt containing adherent 200 mesh particles, which comprises treating an agglomerated compact adhesive coal silt containing a substantial proportion of -200 mesh particles and from 10% to 30% of water by weight of the silt, incorporating with said silt from about .1% to 3% by weight of the silt of the powdered solid form of spent sulfite liquor from paper processing and mixing the powdered solid form of spent sulfite liquor and coal silt to a mixture containing not more than 30% of water by weight of the silt and until the coal silt is breakable by mechanical action.
4. A process of producing non-adherent disintegrated coal fines firom waste coal silt containing adherent --200 mesh particles, which comprises treating an agglomerated compact adhesive coal silt containing a substantial proportion of 200 mesh particles and from 10% to 30% of water by weight of the silt, incorporating with said silt from about .2% to 6% of spent sulfite liquor by weight of the silt, said spent sulfite liquor being from paper processing and containing not more than Water by weight of the liquor, and mixing the spent sulfite liquor and the coal silt to a mixture containing not more than 30% of water by weight of the silt and until the coal silt has been disintegrated and rendered nonadhesive.
5. A method of forming a non-sticky, dry flowable coal dust having a substantial portion of particles of less than 200 mesh from sticky waste coal silt, which comprises treating an agglomerated compact adhesive waste coal silt containing a substantial portion of 200 mesh particles and from 10% to 30% of water by weight of the silt, incorporating with said silt a composition selected from the group consisting of spent sulfite liquor containing not more than 50% of water by weight of the liquor and the powdered solid form of spent sulfite liquor in a proportion of from 0.2% to 6% of said spent sulfite liquor by weight of the silt and from 0.1% to 3% of said powdered solid form by weight of the silt to provide friability and pulverulence to said agglomerated silt and mixing said spent sulfite composition in said silt to cause the disintegration of said silt.
6. Disintegrated non-adhesive waste coal silt comprising particles of silt ranging from 20 mesh particles to 400 mesh particles having from 10% to 30% of water by weight of the silt, said silt having spent sulfite liquor containing not more than 50% of water by weight of the liquor in the proportion of from about .2% to 6% by weight of said silt.
7. Disintegrated non-adhesive waste coal silt comprising particles of silt ranging from 20 mesh particles to 400 mesh particles having from 10% to 30% of water by weight of the silt, said silt having the solids of spent sulfite liquor in the proportion of from about .1% to 3% by weight of said silt.
Ellis Dec. 1, 1914 Ellis Nov. 13, 1917

Claims (1)

1. A PROCESS OF PRODUCING NON-ADHERENT DISINTEGRATED COAL FINES FROM COAL SLIT CONTAINING ADHERENT -200 MESH PARTICLES, WHICH COMPRISES TREATING AN AGGLOMERATED COMPACT ADHESIVE COAL SLIT CONTAINING A SUBSTANTIAL PROPORTION OF -200 MESH PARTICLES AND FROM 10% TO 30% OF WATER BY WEIGHT OF THE SLIT, INCORPORATING WITH SAID SLIT A COMPOSITION SELECTED FROM THE GROUP CONSISTING OF SPENT SULFITE LIQUOR AND THE POWDERED SOLID FORM OF SULFITE LIQUOR, SAID COMPOSITION CONTAINING SOLIDS OF SPENT SULFITE LIQUOR IN A PROPORTION OF ABOUT .1% TO 3% BY WEIGHT OF THE SLIT, AND MIXING THE COMPOSITION AND THE COAL SLIT INTO A MIXUTRE CONTAINING LESS THAN 30% OF WATER BY WEIGHT OF THE SLIT AND UNTIL THE COAL SLIT IS BREAKABLE BY MECHANICAL ACITON.
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2901427A (en) * 1956-05-12 1959-08-25 Chem Fab Grunau Ag Dry fire extinguishing composition
US2907645A (en) * 1957-01-22 1959-10-06 Hartmann Waldemar Method of aggregating carbonaceous material
US4269721A (en) * 1979-12-21 1981-05-26 Stauffer Chemical Company Dust abatement with calcium sulfate

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1119500A (en) * 1914-10-20 1914-12-01 Carleton Ellis Composition for laying road-dust.
US1246807A (en) * 1917-05-02 1917-11-13 Ellis Foster Co Briqueting process.

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1119500A (en) * 1914-10-20 1914-12-01 Carleton Ellis Composition for laying road-dust.
US1246807A (en) * 1917-05-02 1917-11-13 Ellis Foster Co Briqueting process.

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2901427A (en) * 1956-05-12 1959-08-25 Chem Fab Grunau Ag Dry fire extinguishing composition
US2907645A (en) * 1957-01-22 1959-10-06 Hartmann Waldemar Method of aggregating carbonaceous material
US4269721A (en) * 1979-12-21 1981-05-26 Stauffer Chemical Company Dust abatement with calcium sulfate

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