US1860585A - Treatment of sulphide ores - Google Patents

Description

Patented May 31, 1932 UNlTED STATES PATENT OFF-ICE mas nan: traumas, or remit vnnx, NORWAY, AssIeNon 'ro. ra'rnnmx'rmrouaenr GRONDAL-RAMEN, or srooxnonm, swnnmr TREATMENT OF SULPHIIDE ORE-S No Drawing,

- This invention relates to the treatment of sulphide ores, particularly of the pyrite type, and has for its object the provision of an improved method of treating such ores for the a recovery of sulphur in elemental form, and of such valuable metals as the ore may contain. The invention is particularly applicable to the treatment of pyrites containing matteformingmetallic constituents, since it effects a substantial concentration'of the valuable matte-forming; metal values, and permits the recovery of8 fl% or more of the sulphur} as elemental sulphur, thereby reducing to a minimum the discharge of obnoxious smelting gases to the atmosphere. 1 In its complete and preferred aspect the invention involves the combination of an improved method of pyritic smelting with an improved method of treating the resulting smelting gases for the recovery of sulphur in elemental form. The smelting operation is characterized by] suchcomposition of the charge and regulation and control of the op, rierating conditions'that the resulting molten i products retain only such amount of sulphur as is required for-satisfactory ma formaftion and such as is incidentally included in the slag, while the resulting aseousproduct containsthe'remaindero the sulphur largely in the form of'ele'm'ental sulphur and for the rest in the form of sulphur compounds of such compositionand amounts as react to form further substantial amounts of elemental sulphur in the subsequent gas treatment operation. The gas treatment operation is characterized by appropriate condi-- tioning of the gaseous product of the smelting operation for the contemplated mutual interaction of the sulphur compounds therein, and the subsequent eifective condensation and recoveryv of mental sulphurl 1 V The smelting operation of the invention is advantageously carried out in a shaft furnace having a water jacketed bosh section providpractically all of the ele-' 'Application filed July 26, 1930. Serial no. 471,097. I

ed withtwyers, resembling generally the customary blast furnace. I have found, however, (that it is desirable to construct the to provide'the furnace'with a relatively long shaft, say 2 to 3 times theheight of the bosh 55 section, in order to insure adequate'oppor- V tunity, both with respect to time and path of charge progress, foraccomplishingthe contemplated reactions. The top of the furnace is enclosed to prevent the admission of atmoso pheric air and to permit the withdrawal without oxidation of the gaseous roduct for its subsequent treatment. The mace is provided with a double-gated, or otherwise appropriately sealed, charging device to rmit as the introduction of the charge into -t e topof the furnace with minimum admission of alr. V

The charge consists of the pyrite or other sulphide ore to be treated with such flux, such 70 as silica, lime etc., as may be necessa'ry for slag formation. This part of the charge may be made up in substantially the manner heretofore customary 1n pyritic smelting. In accordance with. my present invention, the (5 charge includes in addition up to 10% by weight of a solid carbonaceous material, such as coke,the amount depending on the com position of the ore. The materials of the chargeshould be in the form of lumps, pref- 8D erably not too large in size, with the lumpsof carbonaceous material preferably somewhat smaller than the lumps of ore, In order to give the charge as a whole a substantially uniform porosity. It is im ortant that this 35 porosity of the charge be su h as not to offer any material resistance to the upward passage therethrough of the gaseous products, while at the same time possessing such uniformity as to prevent any channeling or by;

passing of these gases. Moreover, the distribution of the carbonaceous material should be such as to afford adequate opportunity for contact therewith of the ascending sulphur dioxide gas resulting from the pyritic smelting operation near the bottom of the furnace. In large scale commercial operations, it is permissible to charge into the furnace ordinary run of mine ore which may contain some small percentage of fine material. While it is preferable to mix the materials of the charge prior to feeding into the furnace, more particularly in small scale operations, the ore, carbonaceous I material and flux may be introduced into the furnace in separate layers.

The furnace may be started up in any approved manner, and the operation is then regulated and controlled to establish and maintain the reactive zones and conditions characteristic of the invention. Assuming the treatment of a pyrite ore, the principal reaction in the upper zone of the furnace, say, the upper half of the shaft, is the heating of the charge by the ascending hot gases and the elimination or driving ofi by heat (at temperatures of about 500800 C.) of the feeble sulphur atom of the pyrite (FeS In this manner approximately one half of the sulphur is removed. as elemental sulphur and subsequently recovered as such as hereinafter described. In the middle zone of the furnace, say the lower half of the shaft, the ascending sulphur dioxide gas meets and contacts with the now highly heated carbonaceous material (at temperatures of about 7 00- 1100 C. and higher; and is reduced in large part to elemental sulphur with the attendant formation of certain carbon-sulphur compounds. Substantially all of the carbonaceous material included in the charge is preferably consumed in this zone of the furnace, so that in the lower or bosh section of the furnace a practically true pyritic smelting takes place in which the heat resulting from the oxidation of the iron and sulphur by the air blown through the twyersds suificient for slag and matte forming requirements (temperature about 12004500 0.). That part of the iron sulphide (FeS) not oxidized by the air blast unites with the copper sulphide and/or other suitable metallic sulphides present in the ore to form the matte, while the oxidized iron (FeO) combines withthe flux included in the charge to form the slag, and the molten matte and slag are removed from the furnace in any approved manner.

While it is my preferred practice tnat the smelting in the lower zone of the furnace be a practically true pyritic operation, some small proportion of carbonaceous material may reach this zone and be there consumed by oxygen of the blast, without seriously impairing the economic balanceof the process. The oxygen required in the process, however,

is only such amount as is necessaryto oxidize that part of the iron sulphide (FeS') not required for matte-formation. Any substantial consumption of oxygen by carbonaceous material in the smeltingzone is, therefore, at the expense of the iron sulphide, and results in the inclusion of excessive iron sulphide in the matte thereby lowering the grade of the matte and reducing the percentage of sulphur recovery. Moreover, the carbonaceous material required in the process is only such amount as is required to reduce a part (roughly about three-fourth) of the sulphur dioxide formed in the smelting zone (with some additional amount consumed by the resulting elemental sulphur in forming carbon sulphur compounds), so that such carbonaceous-material as combined directly with free oxygen of the air blast is not economically utilized. Considering now the intermediate or middle reaction zone of the furnace, it is my pre-- ,ferred practice to so regulate and control the tion C S0 S CO Some of the resulting elemental sulphur reacts with the hot carbonaceous material (at temperatures of about 8001100 C.) to form carbon disulphide CS The carbon dioxide is reduced in part to carbon monoxide which combines with elemental sulphur to form carbon oxysulphide (COS). In addition, some hydrogen sulphide (H S) is almost inevitably formed under practical operating conditions, but I prefer to limit the formation of this compound to the minimum compatible with operating practice. It is accordingly my aim that slightly more sulphur dioxide should pass unaltered through this intermediate zone than is required to complete in the subsequent catalytic chamber of the subsequent gas treatment operation the reactions indicated by the following equations CS SO CO 38 mos S0 =2CO 3S 211.5 SO =2H O 3S therefore rarely if ever, complete. For this;

reason I prefer to avoid as far as practicable the formation. of hydrogen sulphide. Any

' source of hydrogen, such for example as hy- A good grade of dry metallurgical coke gives 5 a longer period of time for carrying out the satisfactory results in the practice of the invention. The small amount of volatile matter driven off from such a carbonaceous material appears to react with sulphur dioxide in the catalytic apparatus, and consequently does not contaminate the sulphur product.

r In practicing the invention, I have found it advantageous, if indeed not necessary, that the furnace operation be conducted at a considerably slower rate than is customary in ordinary yritic smelting. Thus, where air blast pressures of 100 to 150 mm. Hg (millimefers of mercury) are common in ordinary pyritic smelting, 1 preferably use air blast pressures of 30- to Y 50 mm. H Then .1 preferably use a volume of air o 1000 cubic meters or less per ton of pyrite, as contrasted with about 1500 cubic meters in ordinary pyritic smelting-treating the same ole. Furthermore, where. the total height of the furnace iifordinary pyritic smelting is comparatively low, Ste 12 feet, I preferably employ a furnace twice that height. This lower air blast pressure and volume materially reduce the velocity of gas flow through the furnace,

and the increased height of furnace provides contemplated reactions.

It. is desirable that the charge progress downwardly through thr furnace in as near ly a uniform manner and-rate as possible. Thus, care should be taken to avoid the passage of individual" lumps of elth'er ore or coke at a faster rate than horizontally contiguous or adjacent lumps. To this end the charge should not contain relatively small pieces or lumps or fine material, which may pass too rapidly through the voidsofthe charge, and may moreover impair the desired uniform porosity of the body of charge; As previously pointed out, more latitude 1s permissible in the observance of these conditions in large scale operations. Fine ore, and in particularfiotationconcentrates, may be rendered amenable to treatment 1n ac cordance with-the invention by briquetting, 5 or by other suitable agglomeratlng operations; preferably an operation involving no loss of sulphur such as occurs in sintering;

The gaseous roduct of the furnace operation is substantially neutral in character and comprises for; the most part sulphur vapor, sulphur dioxide, carbon disulphide, carbon oxysulphide, hydrogen sulphide, carbon dioxide and nitrogen. As previously intimated practically no free oxygen is present in these gases. Carbon monoxide is likewise practically absent, rarely being present in greater amount than from 0.1 t-o 0.2% by volume. Such carbon dioxide as is present (in my preferred practice around14l5% by volume) results mainly from the reduction of the ascending sulphur dioxide by the hot carbonaceous material, rather than from any direct combustion of the carbonaceous material by free oxygen, although as previously intimated some direct combustion of the carbonaceoi'is material by free oxygen may take place without seriously impairing economic operation. In addition the exiting gases will carry along with them a certain small percentage of solid particles, such as ore, coke, metallic sulphides, etc.

' For the gas treatment operation of the invention, the gaseous product of the smelting operation should have a temperature of about 400 C. By proper regulation and control of the smelting operation the gaseous product. can be exhausted from the furnace at approximately this temperature. In fact, I have found that such an exhaust gas temperature gives the optimum operating tem' perature conditions throughout the furnace. In'the event the temperature of the gaseous product is too low, it may be appropriately preheated in preparation for the .gas treat-- ment operation, or the furnace charge may be appropriately preheated.

The gaseous-product flows directly from the closed top or throat of the smelting furnace to the gas treatment apparatus. The

natural pressure of this gas, induced by the twyer blast and the furnace draft, is ordinarily sufficient to carry the gaslthrough the entire apparatus. The gastreatment process may conveniently be considered as comprising the following steps: 1 V

(1) Removal of relatively fine'solid par ticles of ore, coke, zinc sulphide, lead sulphide, etc. by electrostatic precipitation, preferably preceded by removal of relatively coarse solid particles 'of ore, coke, etc. in a dust chamber.

(2) Reaction of organic sulphur compounds and hydrogen sulphide with sulphur dioxide in the'presence of a catalyst to form elemental sulphur.-

- (3) Condensationof most of the elemental, sulphur and precipitation of a part thereof in a heat-interchange condenser.

(4) Electrostatic precipitation of the re maining elemental sulphur.

The gaseous product is preferably first passed through a dust chamber or mechanical dust collector, Where relatively coarse solid particles of coke, ore and the like are removed. Only a slight and insignificant drop in temperature takes place in the passage of the gas through this apparatus.

The gas, still at a temperature approximat ing 400 C., now passes through an electrostatic precipitator, where relatively fine particles of solid matter are removed. I have found that this treatment of the gas is particularly advantageous as a conditioning step for the contemplated catalytic reaction, especi ally where the ore contains zinc. The relatively fine particles of carbon, ore, and more particularly zinc or lead sulphide coat or film the catalytic material, and, unless removed, impair and ultimately destroy its ac-v tivity in a few days. In passing through this apparatus the temperature of the gas is slightbe periodically shaken to remove material from the bottom as fresh material is added from time to time at the top. a

It is now my preferred practice to make the catalytic mass or material of hydrate of aluminum or oxide of aluminum containing some proportion of combined water. The aluminum hydrate or oxide is mixed with an appropriate amount of cement to which is added a small amount of aluminum powder. The materials are thoroughly mixed dry, and then calcium hydrate and water are added in such amount as to produce a plastic mass. The mass is placed in boxes where it begins to rise or swell after 40 to 50 minutes forming a porous and blistery product. After some time, depending on the binding capacity of the cement, the mass becomes hard and may be directly used, or may be crushed to pieces of appropriate size.

I have hercinbefore recited the reactions taking place in the catalytic chamber, involving the formation of elemental sulphur from the various sulphur compounds present in the gaseous product of the smelting operation. These reactions are slightly exothermic, and the temperature of the gas rises during its passage through the chamber. The operation is preferably controlled so that the temperature of the gas exiting from the chamber does not greatly exceed 450 C. In my preferred practice of the invention, the temperature of these exiting gases is maintained. about 400 C. a

The gas exiting from the catalytic chamber contains elemental sulphur vapor admixed with a very considerably larger volume of inert gases, for the most part carbon dioxide and nitrogen. The gas will be practically free of sulphur compounds except some small amount of sulphur dioxide ;approximately that amount provided in excess of the quantity required for reaction with other sulphur compounds in the catalytic chamber. Should the sulphur dioxide content of this exit gas be too high, producer gas (00) or other appropriate reducing gas, may be added to the gas as it exits from the catalytic chamber and the resulting gas mixture passed through a second catalytic chamber, similar to the one already described, where the sulphur dioxide will be reduced with the formation of elemental sulphur.

From the catalytic chamber, the gas passes to an apparatus for condensing the elemental sulphur vapor. This apparatus is preferably of the surface condenser or heat-interchange type, where the sensible heat of the gases and the heat of condensation of elemental sulphur may be conserved and economically utilized. I have secured very sat isfactory condensation of the elemental sulphur vapor in a condenser in which the gas is conducted through or between cooling surfaces surrounded by one or more chambers containing water and having one or more steam outlets provided with adjustable automatic valves designed to permit the discharge ofsteam from the chambers at a predetermined constant pressure or pressures. By proper adjustment of these valves, a constant steam pressure and hence a corresponding constant temperature can be maintained in the chamber. The pressure is regulated in ,such a manner that the temperature of the cooling water is maintained at from 112 C to 155 C, corresponding to a pressure of about 1.56 atmospheres (absolute pressure 1.56.0 Kg. per sq. cm.). If the quantity of gas flowing through the condenser increases, more heat is transferred to the cooling water, and an increased amount of the water is evaporated. The temperature of the water will however remain constant since the pressure is automatically maintained constant. On the other hand, when the quantity of gas flowing through the condenser decreases, the cooling water absorbs less heat and evaporation diminishes, but the pressure and the temperature are automatically maintained constant. The water chamber or chambers of the condenser are provided with any appropriate means for supplying water thereto as required. V

In practice, I preferably conduct the cooling of the" gas exitin from the catalytic chamber and the con ensation of the elemental sulphur vapor therein in two 'stages. Condensation of the elemental sulphur vapor takes place when the dew point is reached and about one half of the condensed sulphur is precipitated as molten sulphur and is appropriately 'withdrawn from the condenser. Both stages are carried out in heat interchange apparatus of the character described in the preceding paragraph. From the first stage, high pressure steam at about 4 to 5 atmospheres is obtained, and from the second stage low pressure steam at about 1.5 atmosheres is obtained. The steam so obtained 1s suflicient to generate more than enough power to meet all of the requirements of an ordinary plant.

The exit gas of the surface condenser has a temperature of about 130 C and is conducted to an electrostatic precipitator operated at about 125135 C. Here practically all of the remaining elemental sulphur is precipitated in a molten condition, appropriately withdrawn from the precipitator and mixed with the molten sulphur from the surface condenser, and the resulting molten mixture solidified inany suitable manner. The sulphur product thus recovered represents about 80% of the total sulphur of the pyrite. This sulphur is of high grade, being substantially pure sulphur, and is admirably adapted for the common industrial uses of high grade commercial sulphur or brimstone.

. The gas exiting from the electrostatic sulphur precipitator contains only traces of sulphur'and sulphur compounds (principally sulphur dioxide), and may ordinarily be allowed to escape into the atmosphere. If it is desired to remove all traces of sulphur and sulphur compounds from this gas, it may be heated and passed with an appropriate amount of air into a burner, where the sulphur and sulphur compounds burn to sulphur dioxide. The burner should preferably be provided with a catalytic chamber which facilitates the oxidation of the last traces of sulphur and sulphur compounds. sulphur dioxideis then absorbed by passing the gas through a scrubber containing limestone sprinkled with water, or any other appropriate absorption means, or, the residual sulphur dioxide after burning may be utilized in the manufacture of sulphuric acid. In many instances, passing the gas exitingfrom the electrostatic sulphur precipitator directly through a lime tower or other suitable gas v scrubber will eflect a sufliciently satisfactory removal of the residual sulphur dioxide.

The following example illustrates a practical application of the principles of the invention. It is to be understood that the example is merely illustrative, and is in no sense restrictive of the scope of the invention.

The resulting L The ore was a pyriteof approximately the following composition by analysis Per cent S c. 42.64: SiO 11.18 Zn 1.95 Fe 38.50 Cu L 2.66

The' smelting charge was made up as follows:

v kg. P i Quartz SiO 142 1 Limestone (96% CaCO 33.4 Coke (calculated as net carbon) 70 Return slag 62.4

The bosh section of the blast furnace was about 6 feet high and the shaft section was about .14 feet high :making nace height 20 feet. The air last was ordinary atmospheric air, unheated and undried, and was blown in at a pressure of about 30-50 mm. Hg. and at the rate of 950 cubic metres (calculated at atmospheric tempera-- ture) per 1000 kg. of pyrite. The products 7 resulting from the treatment of each 1000 kg. of pyrite were as follows:

e total fur- Matte 175 kg. i Slag 650 kg.-(approximate) Elemental sulphur 340 kg.

Dust 6kg.

Gaseous product 950 cubic metres (at atmospheric temperature) The gaseous product exiting from the nace contained, in addition to elemental sulphur vapor, nitrogen and carbon dioxide, the following sulphur compounds in "about the amounts specified for each 950 cu. m. of gas, (i. e. per 1000 kg. of pyrite treated) .k Sulphur as CS 2 4 Sulphur as COS 8 Sulphur as H S 4 Sulphur as S0 30 The compositions of the matte and slag were approximately as follows:

The sulphur balance of the complete operation was as follows:

Per cent Sulphur in pyrite 100 Sulphur recovered in elemental form 79.9 Sulphur in matte 101 i Sulphur in slag 4.68 Sulphur in exhaust gases 5.28

The matte resulting from the furnace operation may advantageously be retreated in a closed blast furnace in substantially the same manner as hereinbefore described for treating the pyrite. The gaseous product of this matte treatment will then be subjected to the same sulphur recovery apparatus as hereinbefore described, and there will be recovered as elemental sulphur aofurther 5 to 7% of the sulphur present in the original pyritic ore, thus bringing the total recovery of elemental sulphur to 85% or better. In this retreatment of the matte, a further concentration of the copper is effected, and a matte of 40-50% copper content is obtained.

In the practice of the invention with a pyritic ore containing no matte-forming metal values, a certain amount (approximately that which would ordinarily enter the matte) of the iron sulphide remains unoxidized and being melted at the prevailing smelting temperature is withdrawn from the furnace as a matte together with the slag formed by the oxidized iron and flux. In the application of theinvention to the treatment of iron sulphide ores other than pyrites, such for example as pyrrhotite (Fe S where the ore contains little or no sulphur easily driven off by heat alone, the upper zone of the furnace will be merely a preheating zone to bring the charge to the appropriately high temperature required for reduction of the ascending sulphur dioxide.

By smelting operation I mean that suflicient heat is developed in the lower part of the furnace to fuse or melt the residual charge with the formation of slag and matte. By. sulphide ore or sulphide material I mean to include any and all sulphur-bearing materials amenable to treatment in accordance with the principles of the invention, such as ores, concentrates, metallurgical products and the like.

I claim 2-- 1. The process of producing elemental sulphur from a sulphide ore which comprises smelting a charge of the sulphide ore, flux if necessary, and carbonaceousmaterial in a closed blast furnace so as'to produce a gaseous product containing elemental sulphur, sulphur dioxide, and other sulphur compounds comprising carbon sulphur compounds capable of reacting with sulphur dioxide to produce elemental sulphur, the amount of sulphur dioxide in said gaseous product being at least sufficient to satisfy the reactive repounds in the gaseous product, subjecting and said other sulphur compounds and thereby liberating in elemental form the sulphur of the so-reacting sulphur dioxide and other sulphur compounds, and recovering the elemental sulphur from the so-treated gaseous product.

2. The process of producing elemental sulphur from a sulphide ore which comprises treating a charge of the sulphide ore, flux if necessary, and carbonaceous material in a blast furnace so as to product a gaseous roduct containing carbon disulphide, su phur dioxide, and elemental sulphur vapor, subjecting said gaseous product to the action of a catalyst adapted to promote the reaction of said carbon disulphide and sulphur dioxide to form elemental sulphur, and recovering the elemental sulphur from the so-treated gaseous product.

3. The process of producing elemental sulphur from a sulphide, ore which comprises treating a charge of the sulphide ore, flux if necessary, and carbonaceous material in a blast furnace so as to produce a gaseous product containing carbon disulphide, carbon oxysulphide, sulphur dioxide, and elemental sulphur vapor, subjecting said gaseous product to the action of a catalyst adapted to promote the reaction of said carbon disulphide and carbon oxysulphide with sulphur dioxide to form elemental sulphur, and recovering the elemental sulphur from the sotreated gaseous product.

4. The process of producing elemental sulphur from a pyritic ore which com rises smelting a charge of the pyritic ore, ux if necessary, and carbonaceous material in a closed blast furnace so as to produce a gaseous product containing carbon disulphide, sul phur dioxide, and elemental sulphur, the

amount of elemental sulphur in said gaseous product being substantially in excess of onehalf the amount present in the pyritic ore and the amount of sulphur dioxide in said gaseous product being in excess of the amount required to react with the carbon disulphide to product elemental sulphur, subjecting said gaseous product at an elevated temperature to the action of a catalyst adapted to promote the reaction between 5111- phur dioxide and carbon disulphide and thereby liberating in elemental form the sulphur or the so-reacting sulphur dioxide and carbon disulphide, and recovering the elemental sulphur from the so-treated gaseous product.

5. The process of producing elemental sulphur from a sulphide ore which comprises smelting a charge of the sulphide ore, flux if necessary, and carbonaceous material in a closed blast furnace so as to produce a gaseous product containing elemental sulphur, sulphur dioxide, and other sulphur compounds comprising carbon sulphur compounds capable of reacting with sulphur dioxide to produce elemental sulphur, the

amount of sulphur dioxide in said gaseousother sulphur compounds, and recovering the elemental sulphur from the so-treated gaseous product.

'6. The process of producin elemental sulphur from a pyritic ore -w ich comprises smelting a charge of the pyritic ore, flux if necessary, and carbonaceous material in a closed blast furnace so as to produce a gaseous product containing carbon disulfide, sulphur dioxide, and elemental sulphur, the amount of elementalisulphur' in said gaseous product being substantially in excess of onehalf the amount present in the pyritic ore and the amount of sulphur dioxide in said gaseous product being in excess of the amount requiredto react with the carbon disulphide to produce elemental sulphur, subjecting: said gaseous product to electrostatic precipitation for removing finely divided solid matter therefrom, subjecting the resulting gaseous product at an elevated temperature to the action of a catalyst adapted to promote the reaction between sulphur dioxide and carbon disulphide and thereby liberating in elemental form the sulphur of the so-reactlng sulphur dioxide and carbon disulphide, and recovering the elemental sulphur from the sotreated gaseous product.

7. The method of treating sulphide ore which comprises subjecting a mlxture of the sulphide ore, flux if necessary, and carbonaceous material substantially free from hydrocarbons to a smelting operation in a closed blast furnace and regulating the operating conditions in such manneras to produce at the gas discharge outlet of the furnace a gaseous product containing elemental sulphur, carbon disulphide, carbon oxysulphide, and sulphur dioxide, the latter 1n excess ofthat capable of reacting with the other sulphur compounds. present 1n the gaseous product to form elemental sulphur.

8. The method of treating pyr1t1c ore which comprises subjecting a mixture of the pyritic ore, flux if necessary, and carbonaceous material substantially free from hydrocarbons to a smelting operation in a blast furnace, and regulating the operating conditions in such manner as to drive off from the lower zone of the furnace sulphur dioxide which ascending to the intermediate zone of the furnace contacts with highly heated carbonaceous material to form elemental sulphur and certain carbon sulphur compounds and the resulting ascending gases sufiiciently heat the pyrite in the upper zone of the furnace to drive off its feeble sulphur atom, and withdrawing from the furnace a gaseous product containing elemental sulphur, carbon sulphur compounds, and sulphur dioxide, the latter in. excess 'of that capable of reacting with said carbon sulphur com-- pounds to form elemental sulphur.

9. The method of treating sulphide ore which comprises subjecting a mixture of the sulphide ore, flux if necessary, and carbonaceous material substantially free from hydrocarbons to a smelting operation in a closed blast furnace and regulating the operating conditions in such manner as to produce at the gas discharge outlet of the furnace a gaseous product containin elemental sulphur, carbon disulphide, carbon oxysulphide, and sulphur dioxide, the latter in excess of that capable of reacting with the other sulphur compounds present in the gaseous product to form elemental sulphur, withdrawing said gaseous product from said furnace and causing the sulphur dioxide therein to react with the other sulphur compounds therein to .formr elemental sulphur, and recovering the elemental sulphur from the so-treated gaseous product.

10.- 'The method of treating sulphide ore which comprises subjecting a mixture of sulphide ore, flux if necessary, and carbonaceous material substantially free from hydrocarbons to a smelting operation in a blast furnace, and regulating the operating con- -ditions in such manner as to drive off from the lower zone of the furnace sulphur dioxide which ascending to a higher zone of the furnace contacts with highly heated carbonaceous material to form elemental sulphur and certain carbon sulphur compounds, withdrawing from the furnace a gaseous product containing elemental sulphur, carbon sulphur compounds, and sulphur dioxide, the

latter in excess of that capable of reacting with said carbon sulphur compounds to form elemental sulphur, causing the sulphur dioxide in the gaseous product withdrawn from the furnace to react with the carbon sulphur compounds therein to form elemental sulphur, and recovering the elemental sulphur from the so-treated gaseous product.

11. The method of treating a sulphide material for the production of elemental sulphur and a matte which comprises smelting in a closed blast furnace a charge of the sulphide ore, slag-forming material and carbonaceous material substantially free from volatile matter, the quantity of carbonaceous material not exceeding 10% of the total burden, regulating the air blast of the smelting operation to produce matte and slag and a gaseous product containing a considerable part of the original sulphur of the sulphide material in the form of elemental sulphur together with sulphur compounds capable of reacting to form elemental sulphur, withdrawing the gaseous product from said furand a gaseous product containing a considerable part of the original sulphur of the sulphide material inthe form of elemental sulphur together with sulphur compounds capable of reacting to form elemental sulphur, withdrawing the gaseous product from said furnace and subjecting it to a dust removal operation and then to a catalytic operation in which said sulphur compounds react to form elemental sulphur, and recovering elemental sulphur from the gas exiting from said catalytic operation.

13. The method of treating a charge of sulphide ore, flux if necessary, and carbonaceous material in a blast furnace having means for withdrawing the gaseous product thereof for subsequent treatment which comprises regulating the air blast with respect to the composition of the charge so that smelting takes place in the lower part of the fur- .nace and the gaseous product withdrawn from the furnace contains elemental sulphur, carbon sulphur compounds, and sulphur dioxide. the latter being in excess of the amount required to react with said carbon sulphur compounds to form elemental sulphur, subjecting said gaseous product at an elevated temperature to the action of a catalyst adapted to cause said carbon sulphur compounds to .react with said sulphur dioxide to form elemental sulphur, and recovering elemental sulphur from the so-treated gaseous product.

14. The method of treating a charge of pyrite, flux if necessary, and carbonaceous material in a blast furnace having means for withdrawing the gaseous product thereof for subsequent treatment and in which a smelting temperature is developed in the lower part of the furnace and a sufiiciently high temperature is maintained in the upper part of the furnace to drive off the feeble atom of the pyrite sulphur characterized in that a py-.

ritic smelting takes place in the lower part of the furnace in the absence of any noteworthy consumption of carbonaceous material by free oxygen of the air blown into the furnace in consequence of the fact that the carbonaceous material included in the charge is for the most part consumed above the smelting zone of the furnace in reducing ascending sulphur dioxide and forming carbon sulphur compounds.

15. The method of treating pyrite in a blast furnace equipped with means for withdrawing the gaseous product thereof for subsequent treatment which comprises blowing through the furnace charge of pyrite, flux if necessary, and carbonaceous material an amount of air so proportioned with respect to the composition of the charge that (1) smelting takes place in the lower part of the furnace and (2) a sufliciently high temperature is maintained in the upper part of the furnace to drive off the feeble atom of the pyrite sulphur and (3) a gaseous product is produced in and withdrawn from the furnace containing substantial amounts of carbon disulphide and sulphur dioxide together with elemental sulphur vapor substantially in excess of one-half the amount present in the pyrite.

16. The method of producing elemental sulphur from a sulphide ore which comprises treating a charge of the sulphide ore, flux if necessary, and carbonaceous material in a blast furnace so as to produce a gaseous product containing elemental sulphur, sulphur dioxide, and other sulphur compounds comprising carbon sulphur compounds, the amount of sulphur dioxide in said gaseous product being at least sufficient to satisfy the reaction requirements of all of the other sulphur compounds in the gaseous product to liberate elemental sulphur, subjecting said gaseous product to electrostatic precipitation for removing finely divided solid matter therefrom, subjecting the resulting gaseous product at an elevated temperature to the action of a catalyst adapted to cause said sulphur dioxide and said other sulphur compounds to react to form elemental sulphur, cooling the resulting gaseous product to a sufficiently low temperature to condense the elemental sulphur for the most part and to recover a substantial amount of the condensed sulphur in molten form, and subjecting the exiting gases of said cooling operation to electrostatic precipitation to recover substantially all of the elemental sulphur remaining -therein. V

17. In the treatment of gases containing sulphur dioxide and other sulphur compounds capable of reacting therewith to form elemental. sulphur, the steps of subjecting said gas to electrostatic precipitation for removing finely divided solid matter therefrom, and then subjecting the gas at an elevated 18. The method temperature to the action of a catalyst adapted to cause said sulphur dioxide aud'said other sulphur compounds to react to form elemental sulphur.

sary, and carbonaceous material to a smelting capable of-reacting with sulphur dioxide form elemental sulphur, subjecting sa d of producing elemental sulphur from a sulphide orewhich comprises subjecting the sulphide ore, flux if necesgas comprising for the most part carbon dioxide and nitrogen. o

:In testimony ,where'of I have signed my name to this specification.

NILS ERIK LENANDER.

gaseous product to electrostatic precipita f tion for removing finely divided solid matter therefromysubjecting the resulting gas at an elevated temperature to the action of a' catalyst adapted to cause said sulphur dioxide and said other sulphur compounds to react to form elemental sulphur, and recovering elemental sulphur from' the so-treated gas. p 19. The method of treating a char obi-e,

sulphide ore, flux if necessary, and car ona ceous materiahina blast furnace equipped with means for withdrawing the gaseous .1

product thereof for subsequent treatment which comprises regulating the air blast with respectto the'composition of the charge so that smelting takes place in the lower part of the furnace'and the gaseous product withdrawn from the furnace contains elemental bon disulphide, and sulphur disulphur, oxide admi ed with a considerably larger volumeof inert as comprising for the most part carbon dioxide and nitrogen. r

a 20. The method of treating a charge of sulphide ore, flux if necessary, and carbonaceous material in a blast furnace equipped with means for withdrawing the gaseous product of the furnace operation for subsequent treatment, which comprises maintaining a relatively high column of charge above the smelting zone of the furnace, and blowing air into the smelting zone at relatively low pressure andin such volume with respect to the composition of the charge that smelting takes place in the lower part of the, furnace and the gaseous product withdrawn from the furnace contains elemental sulphur, sulphur dioxide, and other sulphur compounds admixed with. a considerably larger volume of inert "gas comprising for the most part carbon di'-" CERTIFICATE OF CORRECTION.

Patent No. 1,860,585. May 31, 1932.

ms ERIK LENANDER.

it is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 1, line 48, strike out the parenthesis page 2, line 37, after the word "higher" strike out the semi-colon and insert the parenthesis same page, line 78, for "three-fourth" read three-fourths, and line'83, for "combined" read combines; page 4, line 28. for "Beauxite" read Bauxite, and line 80, for "Go" read CO; page 6, line 80, claim 2, for "product" read produce; and that the said Letters Patent should be read with these eorrections therein that'the same may conform to the record of the case in the Patent Qffice.

Signed and sealed this 32th day of July, A. D. 1932.

M. .E. Moore,

(Seal) Acting Commissioner of Patents.