US1231831A - Process of treating materials. - Google Patents

Description

tmrrn snare PATENT onnron.

FREDERICK W. YOST, OF CHICAGO. ILLINOIS. ASSIGNOR TO EDWARD A. BERN, OF CHICAGO, ILLINOIS.

PROCESS OF TREATING MATERIALS.

Specification of Letters Patent.

Patented July 3, 1191i 7.

Renewed October 10. 1912. Serial No.

To 0?] 10720112 it may concern.

Be it known that I. Fnnmznrcn W. YosT, a citizen of the I'nited States, residing at Chicago. in the county of (00k and State of Illinois. have invented certain new and useful Improvements in Processes of Treating Materials. of which the following is a SPQCI? fication.

My invention relates to thetreat-ment of material: and it comprises a process wherein a mass of material is calcinedfroasted or clinkered by means of a current of reactionsupporting gas conducted through the mass and by means of heat applied to the gas en- 'trance surface-of the mass during the period of reaction: and it comprises more particularly. but not exclusively. a process wherein a body of furnace gases is used to heat the upper surface of a stationary or movable mass of finely divided material and all or a partof the furnace gases are conducted through the mass to propagate a calcinin roasting. or clinkering reaction through the mass: all as more fully hereinafter set forth and as claimed.

Many ores and minerals liminary change in their physical condition or chemical state to better adapt them for use in metallurgical or manufacturing arts. Finely divided iron ores. blast furnace flue dust. iron ore concentrates and other similar materials arezulvantageously clinkered to fit them for use in the blast furnace, and when these materials have aQhigh sulfur content they also require roastin For special metallurgical purposes it may be desirable to reduce these materials to lower oxids of iron or to sponge iron. Sulfid ores are roasted to partially or wholly convert them into oxids to meet the requirements of various smelting and refining operations. Sulfid ore fines or concentrates require clinkering to adapt them for smelting in stack furnaces and to avoid the more. expensive method of smelting in reverberatory furnaces. Materials like chrome ore, magnesite, bauxite and clay. are calcined to eliminate chemically combined water or carbon dioxid. Finely groimd mixtures of clay and limestone or suitable equivalents of these materials. are calcined and clinkered to make cement clinker. In certain prior applicarequire $01119 PIG- tions now matured into Patents 1,003,682, 1.003.683 and 1,003,6Si. all of September 19, 1911, I describe and claim processes which comprise forming such material into a mass adapted for the propagation of one or more of the described reactions, initiating a reaction at a surface of the mass. conducting a reaction-producing or reaction-supporting gas through the mass toward the surface of initial reaction, and by suitable control of conditions propagating one or more of the described reactions through the mass in one or more directions. In another and c0- pending application, erial Number 551L712, filed April 11. 1910. I describe and claim a process which comprises forming similar materials into-a mass adapted for the propagation of one or more of the described reactions. initiating a reaction in the mass, conducting two currents of reaction-producing or reaction-supporting gas through the mass in difi'erent directions, and by suitable control of conditions propagating one or more of the described reactions through the mass. In these prior processes the calcining. roasting or clinkering reaction is usually propagated through a portion of the mass in a direction opposite to that of the gas current. and this portion of the mass must have a relatively large content of fuel. In the present invention the reaction is propagated through the entire mass in the same direction as that of the reactionsupporting or reaction-producing gas. and the fuel content of the mass can therefore be reduced to the lowest attainable limit. The adaptability of the present process to the treatment of material containing the minimum quantity of naturally or artificially mixed fuel. is one of the important objects of the invention. In the older and discontinuous forms of pot roasting processes, a layer of ignited fuel or of hot calcines is interposed between the material to be clinkered and the grate in the lower part of the pot roasting apparatus. The heat transmitted from this layer of fuel or of hot calcines. to the lower portion of the charge is used to initiate the clinker-ing reaction: but the clinkering zone is propagated through the body of the charge solely by the internal combustion of the contained fuel. In the continuous form of the pot roasting process the moving hearth carries the charge under a suitable. burner or igniting device. where the upper surface of the charge is ignited; and the moving hearth then carries the ignited portion of the charge away from the burner and over a suitable suction box. where a downward draft of air is conducted through the charge. The igniting flame acts on the upper surface of a given portion of the charge for a very short period of time. and the clinkering zone is propagated through the body of the charge wholly by the heat developed by the internal combustion of the fuel in the charge while the steadily entering cold air serves to reduce the temperature at the surface of the charge. The various forms of the pot roasting process have been applied principally to the clinkering of metallic sulfids relatively high in sulfm: Such material is adapted for treatmentby pot roasting because a relatively small amount of heat suflices to ignite the charge. and when ignited a clinkering .reaction can be readily propagated through the charge by a current of cold air. introduced at the ignited surface and conducted through the interior of the charge. It is evident that none of the various forms of the pot roasting process is well adapted for the clinkering of metallic sulfids very low in sulfur. or to the clinkering of artificial mixtures of metallic oxids with carbonaceous fuel. such as finely divided coal or coke which have a relatively high igniting temperature. In the present proces such materials may be readily and economically treated. because the charge may be maintained under the influence of the heating gases during the entire period of operation. and the clu'rent of gases used to propagate the reaction may be conducted through the charge at any required temperature and may have any desired composition. The ability to treat material containing small percentages of fuel and having a high temperature of reaction. is another one of the important objects of the present invention.

My present proces can be carried on discontinuously in any reverberatory roasting furnace provided with a perforated hearth, or it can be carried on continuously in well known forms of chain grate stoker furnaces. The particular form of apparatus used for carrying on this process. is not material to the present invention in its broader aspects.

My proce may be applied to a mass of any pulverous or granular material which is capable of undergoing an internal propagative reaction. whether this capability is natural to the material. as in sulfid ores: or whether it is'imparted by the artificial admixture of reaction-supporting materials with the other materials of the mass. as by the mixing of powdered fuel with finely diof fine Mesaba ore or blast furnace flue dust.

may be mixed with powdered fuel such as bituminous coal screenings. coke breeze or anthracite coal dust, to form a mass adapted for treatment'by my process; materials intended for making Portland cement. such as pulverized mixtures of clay and limestone either naturally or artificially mixed. or

partly naturally and partly artificially mixed. may he treated by my proces by first adding to the material a finely divided fuel: or materials like chrome ore. magnesite. bauxite or clay. which by ordinary methods are not readily calcined. may be mixed with suitable fuel and treated by my process in which the fine state of division and the intimate contact of the material with the fuel materially hastens the calcining operation. Many other materials which are capable of undergoing a propagative reaction when formed into a suitable mam. may be treated by my procesa and I regard its application to all such materials as within the scope of my invention.

As an advantageous embodiment of the invention. my procemmay be applied to the clinkering of finely divided iron oxid. This material may be a pulverous natural ore. the granular product of a concentration process or a finely divided metallurgical waste such as blast furnace flue dust or fine pyrites cinder. The fine iron oxid is mixed with powdered coal. coke. charcoal or other combustible material. and is charged into any suitable furnace of one of the types referred to. Any fuel adapted for use in a reverberatory furnace. may he used to generate flame or furnace gases. which are conducted through the furnace in contact with the upper surface of the charge. A. portion or preferably all of the furnace gases are conducted downward through the charge. and through the perforated hearth or grate into a suitable outlet flue. The charge is heated uniformly and progressively from the top to the bottom. and a clinkering reaction initiated at the upper surface is propagated downward through the charge. but ata slower rate than the progress of the heating zone. The furnace gases must be maintained at a high enough temperature to initiate the clinkering reaction at the upper surface of the charge.'and the gases must also be sutficiently oxidizing to propagate the reaction through the charge. 'hen the process is carried on discontinuously in a reverberameanest tory furnace with a fixed perforated hearth, it is desirable to discontinue the downward current of gases while a layer of unclinkered and cold material remains adjacent to the perforated hearth, to cool the outgoing waste gases to a safe temperature before their passage through the perforated hearth. If preferred a-layer of crushed limestone, clinker or other suitable material may be interposed between the perforated hearth and the lower surface of the charge to absorb the excess of heat in the escaping gases, and the clinkering reaction may then be propagated to the lower surface of the charge. The process may also be carried on discontinuously in a chain grate stoker type of furnace or any other type of movable hearth furnace by holding the charge at rest in the furnace during the time of treatment and then moving the charge so as to carry the clinkered material out of the furnace chamber and a new charge of material into the furnace for treatment. When the process is carried on continuously in a chain grate stoker type of furnace, the charge moves continuously from the entrance end of the furnace to the exit end, the furnace gases are continuously generated by the combustion of extraneous fuel, and all or a portion of these gases are continuously conducted downward through the charge and into a suitable outlet flue. By suitably regulating the speed of the moving hearth, the charge maybe brought to the exit end of the furnace with a heat insulating layer of unclinkered and cold material adjacent to the hearth, and this unclinkered portion of the charge may be screened out of the finished clinker and may be returned to the furnace for retreatment. When a layer of crushed limestone or crushed clinker is fed upon the moving hearth to serve as the heat insulating layer, a part of this layer fuses to the clinkering portion of the charge; and the remaining part of this layer may be separated from the finished clinker by screening and may be re-used in the furnace. carbonaceous material in the charge need only be sufiicient to cause the clinkering reaction to be initiated, since the charge is heated up to the reacting temperature by the furnace gases. When it is desired to produce clinker containing the lower oxids of iron, or

. wholly reduced ing conditions Within the metal such as sponge iron, it to maintain more highly reduccharge than those is necessary Such highly reducing conditions may be secured by the use of larger propor- 60 tions of carbonaceous material in the charge and'by the use of reducing furnace gases.

My process may also be used for roasting and clinkering finely divided sulfid ores, concentrates or flue dust. The finely divided sulfur bearing material is charged into one The i of the types of furnace referred to, and furnace gases generated by the combustion furnace in contact with the upper surface of the charge. of the furnace gases are conducted downward through the charge. and through the perforated hearth or grate into a suitable outlet flue. A clinkering reaction is initiated at the upper surface of the charge and is propagated downward to the lower surface by suitably controlling the composition, temperature and pressure of 'the furnace gases. When it is desired to use the waste sulfur gases for sulfuric acid manufacture or other by-product purpose, the furnace gases may be wholly composed of atmos pheric air highly heated so that they will initiate the clinkering reaction. 'hen the material to be heated is too low in sulfur for the propagation of the clinkering reaction, other elements may be added to the charge.

When this process is applied to the clinkering of cement materials, the finely ground raw mix is intimately mixed with powdered carbonaceous material, such as coal, coke, or charcoal and is charged into a suitable furnace of one ofthe types described. The

of a suitable fuel. are conducted through the A portion or preferably all furnace gases generated by the combustion of a suitable fuel, are'conducted through the furnace in contact with the upper surface of the charge to initiate a clinkering reaction at that surface, and the furnace gases conducted downward through the charge are used to propagate the clinkering reaction to the lower surface. The process may be carried on discontinuously in a fixed hearth furnace or continuously in a furnace of the chain grate Stoker type, and the method of operation maybe similar in a general way to that used for making iron ore clinker.-

In the treatment of the materials described in these examples, various modifications will suggest themselves to those skilled in the art. It may be desirable to moisten the charge to form interstices for the uniform distribution of the gas current through the niass. The furnace gases used to heat the upper surface of the charge and conducted through the charge, may be oxidizing, neutral or reducing. The temperature in the zone of reaction may be regulated or the character of reaction maybe varied by the addition of steam or other modifying elements, to the gas current conducted through the mass. Vhere the ash from the combustion of solid fuel is an undesirable ingredient of the finished product, liquid or semi-liquid fuel may be used as the heat developing component. With material of a highly refractory nature, it may be desirable to add a flux to lower the clinkering temperature. When the process is carried on continuously in a chain grate stoker type of furnace, the furnace gases may be conducted through the furnace chamber in the same direction as that of the moving charge or in the opposite direction.

I do not wish to be limited to the treatment of the materials described in the examples, nor do I wish to be limited to the kinds of treatment there described. It will be evident to those skilled in the art that this invention applies to the treatment of any material, or any mixture of materials, of such a nature that one or more reactions can be propagated through the mass in the same direction as that of a current of gas which is conducted through the mass under the influence of heat applied in the manner described. Itwill be further evident that the kinds of treatment accorded the material are not limited to calcining, roasting, or clinkering, but may include any treatment, which can be carried on by the methods described.

It will also be evident that the gas current can be either an oxidizing or a reducing agent, provided that under suitable control .of conditions it has the property of propagating the reaction in the manner described.

It is to be understood that the words finely divided, as herein used, have reference to any degree of subdivision that best adapts the'material to treatment by my process, as some materials respond to treatment better when=in a relatively coarse condition while other materials respond to treatment only when in afinely divided state. It is to be also understood that where the materials are described in the claims as containing various components, the various components maybe originally contained in the material or they may be added to the material to prepare it for treatment.

Vhat I claim is:

1. The process of treating finely divided material capable of being clinkered, which comprises heating a surface of a mass of the material dining the whole time of treatment, introducing a current of gas at the same surface of the mass, conducting the current of gas through the mass, and controlling conditions so as'to propagate a clinkering reaction through the mass.

2. The process of treating finely divided material containing combustible components, which comprises heating a. surface of a mass of the material during the whole time of treatment, introducing a current of gas at I the same surface of the mass, conducting the current of gas through the mass, and controlling conditions so as to propagate a clinkering reaction throughthe mass.

3. The process of treating finely divided material capable of being clinkeled, which comprises maintaining a body of hot gases in contact with a surface of a mass of the material, conducting hot gases through the mass from the same surface, and controlling conditions so as to propagate a clinkering reaction through the mam.

l. The process of treat-ing finely divided material containing combustible components, which comprises maintaining a body of furnace gases in contact with a surface of a mass of the material. conducting furnace gases through the mass from the same sur face. and propagating a clinkering react-ion through the mass.

5. The process of treating finely divided material containing combu tlblE components,

which comprises transmitting heat from a moving body 'of furnace gases to substantially the entire surface of a mass of the material undergoing treatment, conduct-ing furnace gases through the mass from the same surface. and propagating a clinkering reaction through the mass.

6. The process of treating finely divided material capable of being clinkered, which comprises forming a mass of the material on a perforated furnace-hearth, heating a surface of the mass with a reverberatory furnace flame, introducing a current of gas at the same surface of the mass, conducting a current of gas through the mass, and controlling conditions so as to propagate a clinkering reaction through the mass.

7. The process of treating finely divided material containing combustible components, which comprises forming a mass of the material on a perforated furnace-hearth, transmitting heat from a body of reverberatory furnace gases to a surface of the mass, con

ducting hot gases through the mass from the same surface, and propagating a clinkering reaction through the mass.

8. The process of treating finely divided material containing carbonaceous components, which comprises forming a mas of the material on a. perforated furnace-hearth, transmitting heat from a body of reverberatory furnace gases to a surface of the mass, conducting hot gases through the mass from the same surface. and propagating a clinkering reaction through the mass.

9. The process of treating finely divided material containing combustible components, which comprises forming a mass of the material on a perforated furnace-hearth, main taining a body of reverberatory furnace gases in contact with a surface of the mass, conducting hot gases through the mass from the same surface, and propagating a clinkering reaction through the mass.

10. The process of treating finely divided material capable of being clinkered, which comprises forming a mass of the material on aperforated furnace-hearth, heating the upper surface of the mass with a reverberatory furnace flame, conducting a current of gas downward through the mass, and controlling conditions so as to propagate a clinkering reaction through the mass.

ll. The process of treating finely divided material containing combustible components. which comprises forming a mass of the material on a. perforated furnace-hearth. transmitting heatfrom a body of reverberatory furnace gases to the upper surface of the mass. conducting hot gases downward through the mass. and propagating a clinkering reaction through the mass.

12. The process of treating finely divided material containing carbonaceous components. which comprises forming a mass of the material on a perforated furnace-hearth, maintaining a body of reverberatory furnace gases in contact with the upper surface of the mass. conducting hot gases downward through the mass, and propagating a clinkering reaction throughthe mass.

13. The process of treating finely divided material containing combustible components, which comprises forming a layer of heat insulating material on a perforated furnaceheart-h, charging a mass of the finely divided material on the layer of heat insulating material. transmitting heat from a body of reverberatory furnace gases to the upper surface of the mass, conducting hot gases downward through the mass, and propagating a clinkering reaction through the mass.

It. The process of treating finely divided material containing carbonaceous components, which comprises forming a layer of heat insulating material on a perforated furnace-hearth,charging a mass of the finely divided material on the layer of heat insulating material, maintaining a body of reverberatory furnace gases in contact with the upper surface of the mass, conducting hot gases downward through the mass, and propagating a clinkering reaction through the mass.

15. The process of treating finely divided material containing combustible components, which comprises forming a movable mass of the material on a perforated furnace-hearth, transmitting heat from a body of reverberatory furnace gases to a surface of the movable mass, conducting hot gases through the movable mass from the same surface, and propagating a clinkering reaction through the movable mass.

16. The process of treating finely divided material capable of being clinkered which comprises forming a movable mass of the material on a perforated furnace-hearth, transmitting heat from a body of reverberatory furnace gases to the upper surface of the movable mass, conducting hot gases downward through the movable mass, and controlling conditions so as to propagate a clinkering reaction through the movable mass. Y

17. The process of treating finely divided material containing combustible components, which comprises forming a movable mass of the material on a perforated furnacehearth. transmitting heat from a body of reverberatory furnace gases to the upper surface of the movable mass, conducting hot gases downward through the movable mass, and propagating a clinkering reaction through the movable mass.

18. The process of treating finely divided material containing carbonaceous components. which comprises forming a movable mass of the material on a perforated furnace-hearth, maintaining a body of rever beratory furnace gases in contact with the upper surface of the movable mass, conducting hot gases downward through the movable mass, and propagating a clinkering reaction through the movable mass.

19. The process of treating a finely divided oxid-ore mixture containing combustible components. which comprises forming a movable mass of the mixture on a perforated furnace hea rth. transmitting heatfrom a body of reverberatory furnace gases to the upper surface of the movable mass. conducting hot gases downward through the movable mass, and propagating a clinkering reaction through the movable mass.

20. The process of treating a finely divided oxid-ore mixture containing combustible components, which comprises forming a movable mass of the mixture on a perforated furnace-hearth. interposing a layer of heat insulating material between the perforated hearth and the oxid-ore mixture, maintaining a body of reverberatory fur nace gases in contact with the upper surface of the movable mass. conducting-hot gases downward through the movable mass, and propagating a clinkering reaction through the movable mass.

2L The process of continuously treating finely divided material capable of being clinkered, which comprises continuously feeding the material to a moving perforated furnace-hearth to form a moving mass of the material. continuously heating the upper surface of the moving mass with a reverberatory furnace flame. continuously conducting a current of gas downward through the moving mass, and controlling conditions so as to continuously propagate a clinkering reaction through the moving mass.

22. The process of continuously treating finely divided material containing combustible components, which comprises continuously feeding the material to a moving perforated furnace-hearth to form a moving mass of the material, continuously transmitting heat from a body of reverberatory furnace gases to the upper surface of the moving mass, continuously conducting hot gases downward through the moving mass, and continuously propagating a clinkering reaction through the moving mass.

23. The process of continuously treating finely divided material containing carbonaceous components, which comprises continuously feeding the material to a moving perforated furnace-hearth to form a moving mass of the material. continuously transmitting heat from a body of reverberatory furnace gases to the upper surface of the moving mas continuously conducting hot gases downward through the moving mas, and continuously propagating a clinkering reaction through the moving mass. 7

2- The process of continuously treating a finely divided oxid-ore mixture containing combustible components, which comprises continuously feeding the mixture to a moving perforated furnace-hearth to form a moving mass of the mixture, continuously transmitting heat from a body of reverberatory furnace gases to the upper sin-face of the moving mass, continuously conduct-ing hot gases downward through the moving mass, and continuously propagating a clinkering reaction through the moving mass.

25. The process of continuously treating a finely divided oxid-ore mixture containing combustible components, which comprises continuously feeding a layer of heat insulating material to a moving perforated furnace-hearth, continuously feeding the oxidore mixture on top of the heat insulating layer to form a moving mass, continuously transmitting heat from a body ofreverberatory furnace gases to the upper surface of the moving mass, continuously conducting hot gases downward through the moving mass, and continuously propagating a clink ering reaction tln'ough the oxid-ore mixture.

26. The proce of continuously treating finelyv divided iron oxid, which comprises mixing with the iron oxid the minimum quantity of finely divided fuel required to form a mixture capable of being clinkered; continuously feeding a layer of heat insulating material to a moving perforated furnace-hearth; continuously feeding the iron oxid mixtru'e on top of the heatinsulating layer to form a moving mass; continuously transmitting heat from a body of reverberatory furnace gases to the upper surface of the moving mass: and continuously conducting hotgases downward through the moving mass; the conditions relating to the composition of the iron oxid mixture, the composition, temperature and pressure of the hot gases, and the speed of the moving hearth, being so correlated as to continuously initiate a clinkering reaction at the upper surface of the moving mass, and so as to continuously propagate the clinkering reaction downward through the moving mass.

In testimony whereof I have hereunto set my hand this 28th day of April, 1910, in the presence of two witnesses.

FREDERICK w. YOST.

Witnesses War. P. McMUxx, EDWARD A. BERN.