DE1152716B - Process for roasting iron sulfides - Google Patents

Description

Method for Roasting Iron Sulphides The invention relates to Roasting of iron sulfides, e.g. B. pyrite, pyrrhotite, etc., usable for the purpose of production Sulfur dioxide and useful iron oxides of any useful level. the Invention enables the roasting of iron sulfides with compounds of copper and / or nickel and / or cobalt are contaminated in order for the production of sulfuric acid to obtain suitable sulfur dioxide and iron oxide, directly or indirectly is suitable for the production of high-quality iron and steel. Also delivers a such roasting process economically usable heat that is used for steam generation can be.

Iron pyrites are used extensively in the production of sulfuric acid by burning the pyrite to sulfur dioxide, which in turn is used after washing and other preparatory measures according to known methods in sulfuric acid is converted. The residue from the roasting process is either depending on its content discarded or for the purpose of using the raw materials as completely as possible as blast furnace charging used for iron and steel production. When impurities in the iron pyrite raw material are not removed before, during or after the roasting process, they appear in the Sulfur dioxide gas or in the burn.

The composition of iron pyrite determines that obtained during roasting Products. In addition, the roasting conditions determine the type and texture to a large extent of the products received. The roasting of practically pure iron pyrite can be too practical pure ferric oxide and sulfur dioxide, depending on the roasting conditions. However, practically pure or high quality iron pyrites are in the world nowadays present in limited quantities, and their supply is rapidly diminishing while natural Contaminated or impure iron pyrite stocks are more prevalent. It has hence the need to develop new processes for economic Roasting such impure pyrites for the purpose of producing easily usable sulfur dioxide and residual iron oxide.

Impurities are particularly difficult to remove from pyrite Compounds of copper, nickel and / or cobalt, especially copper compounds. In normal roasting operations, impurities in these compounds appear as insoluble Components of the burn-up, the long and arduous separation or cleaning processes must be subjected to in order to be roasted suitable for the production of iron Offer. An economically used method of removing copper contaminants consists in the burning of a chlorinating roast with subsequent Undergoing leaching to remove copper. This method is effective, however expensive.

So far, a process known as sulphating roasting has been used Roasting copper-containing iron pyrite available in order to obtain leachable burn-off, which is suitable for the production of iron. This procedure will be tightly controlled low temperatures, e.g. B. well below 700 ° C, and excess amounts of oxygen used to convert the copper content of the pyrite into copper sulfate, which is water soluble is, while very little ferric sulfate is formed from the ferric oxide in the burnup. The process solves the task of processing burned-offs contaminated with copper, but supplies large amounts of sulfur trioxide and of course sulphates, which leads to high sulfur losses means.

High temperatures in the roasting stage can reduce the amount of sulfur trioxide and reduce the sulphate loss, but the copper in the burn-up is due to the formation rather insoluble from cupriferrite and therefore difficult to remove. One Reduction of the ratio of oxygen to pyrite in the roasting process for the purpose A reduction in the formation of sulfur trioxide leads to an incomplete conversion from copper to copper sulfates or oxides and leaves a big one Amount of hard-to-remove copper or iron sulfides in the burn-off. Another one Decrease in the ratio of oxygen to pyrite leads to incomplete Oxidation of sulfur to sulfur dioxide, with the result that the roasting gases elemental sulfur is carried along and unoxidized sulfide. remain in the burn. Elemental sulfur must be removed from the roasting gases to prevent sulfur loss and avoid the build-up on the heating pipes and decomposition of the rest of the system to avoid, whereby their effective operation would be disturbed. Also the accruing must Roasted goods of a complicated and expensive leaching or subsequent roasting measures be subjected to; because sulphides consume in the burnup. large amounts of leachant. So while a smaller amount of oxygen facilitates the formation of sulfur trioxide can, it is contrary to the purpose of a sulphating roasting, d. i.e., it prevents a reduction in the amount of insoluble copper in the roast and the possibility of one economic leaching of the roasted material.

The invention has set itself the task of making contaminated pyrites, especially those that are contaminated with copper or cobalt or nickel, Sulfur dioxide, which is easily convertible to sulfuric acid, and an iron oxide residue, which is free from disturbing amounts of impurities, or at least one iron oxide residue, from which such impurities are easily and cheaply removed practically completely can be manufactured in a simple, straightforward and economical process.

If finely divided pyrites, the copper, nickel and / or cobalt as Containing impurities are roasted to practically free magnetite (Fe304) By producing ferric oxide, the ash produced or the burn-off can be leached out to remove substantial amounts of the impurities and thereby iron oxides that are considerably more valuable for iron or steel manufacture. It has also been shown that by controlling the temperatures and amounts of oxygen In the roasting process a sulfur dioxide is obtained which is practically free of sulfur trioxide and sulfur fumes and is therefore in favor of the economical production of sulfuric acid suitable. If, for example, finely divided iron pyrites of a certain composition, which contain copper, nickel and / or cobalt as impurities, in one Fluidized bed at a temperature of about 700 ° C, preferably about 800 ° C, but not above 900 ° C in the presence of oxygen in an amount of about 94 to 103%, preferably about 100 to 1.02% of the amount necessary to roast the whole sulphide content of the pyrite to sulfur dioxide and the whole iron content To oxidize the pyrite to magnetite, a burn was obtained which surprisingly could be easily leached to remove disruptive amounts of these impurities, while sulfur dioxide was obtained at the same time, it was practically free of sulfur trioxide and sulfur vapors were and therefore easily in a state of sulfuric acid generation could be brought. It was found that temperatures above this range ferrites that are insoluble as a result of the reaction of the impurities with the iron in the pyrite and increase sulfur sublimation, which leads to sulfur fumes that contaminate the roasting gases. On the other hand, it turned out that temperatures are favorable below this range sulfur trioxide formation at the expense of sulfur dioxide in the roasting gases, increase the amount of disruptive dust in the roasting gases and set the economical use of heat from the roasted material. Sulfur trioxide formation increases sulfur loss and creates costly cleaning difficulties before sulfuric acid production. Amounts of oxygen above the above range increase the formation of sulfur trioxide, which leads to the disadvantages mentioned above, and also increase ferrite formation with impurities to provide an impure one Burn-off that can only be in an expensive way or not at all in a state for Bring iron production. Oxygen in amounts below the stated range leads to an incomplete conversion of the total sulfur into sulfur dioxide and delivers large amounts of sulphide sulfur in the burn-up, which then produces unusual amounts Leaching solution consumes, and leads to elemental sulfur vapors in the roasting gas, what with expensive cleaning difficulties before ornamental sulfuric acid production is connected from such roasting gases. In addition, the amount of sulfur dioxide in the Roasting gases considerably reduced. The ones used for a particular pyrite Temperatures and amounts of oxygen are critical to this extent and cannot can be greatly modified.

Any previously known method can be used for the formation of the fluidized bed or device are needed. Many methods and devices for heat dissipation from the layer are known and can be applied to the method from the to derive the greatest economic benefit. The usual roasting gas treatment methods and devices and the usual leaching methods and devices are used for Preparation of the roasting gases or the roasted material for the sulfuric acid production or Iron making applied. Overall, the method according to the invention in one existing system or using existing procedures or also in of a new system and / or using new procedural measures will.

Any device and / or mode of operation instead of a fluidized bed can be used to practice the invention, albeit by the fluidized bed method is currently preferred for its efficiency and ease of operation.

The hot burn-off that arises from the roasting process according to the invention, should not be allowed to oxidize after it has been removed from the roaster. He should be in Absence of oxygen e.g. B. be cooled by quenching to the formation of ferric oxide and the resulting ferrite formation with the copper, nickel and resp. or cobalt impurities to avoid converting the impurities into an insoluble and undeniable form.

All iron pyrites contaminated with copper, cobalt and / or nickel can be roasted according to the method of the invention to those described above to achieve surprising advantages. For example, there are roast residues with under 0.10 / 0 reduced impurities of copper, cobalt and / or nickel extremely valuable for the Position high quality iron, and it exists there is currently a strong need for this in the iron and steel industry. If the The content of impurities in the leached combustion is more than 0.8 percent by weight, other cleaning methods, e.g. B. chlorinated roasting, economically feasible because the extraction value of the copper reduces the cost of chlorinating roasting and re-leaching out. The roasting process according to the invention is simplified So not just the method of reducing copper, nickel and / or cobalt impurities in the leached burn-off, but it also allows economic use of iron pyrite, which has so far been used because of its impurities in copper, cobalt and or or nickel could not be used.

Pyrites, as residues from the flotation concentration of sulphide ores are used with advantage, although pyrites obtained in other ways ground or to the appropriate size for setting a sufficiently resistant Fluidized bed crushed can also be used.

The following examples illustrate the invention in particular. Here in All percentages and amounts relate to weight and all temperatures on the centigrade scale. Examples 1 to 7 Those in the following Examples 1 to 7 pyrites used contained about 50.0% sulfide sulfur, .about 44.80io iron and about 0.25% copper; the remainder not calculated was less than 1 / =% from moisture and other contaminants. The particle size of the used Pyrite was smaller than 0.5 mm. The pyrites were evenly bottomed in a fluidized bed reaction vessel fed just above the air inlet, and the operating conditions. the each used in one example can be found in Table 1. The temperature in each experiment was 800 ° C. during the entire throughput.

Table 11 should be viewed in conjunction with Table 1 because they a product analysis of seven samples, drawn in the same numerical order, the roast residue. indicating that made by roasting the original seven specimens and leached by various different leaching methods. Practically any applicable leaching technique can be used, but is based on the list the last column, entitled "Applied Leaching Method", on a leaching of 50 g each with 200 ml aqueous solution, and the letters A to J in this Column mean the following caustic solutions: A. A 20% sulfuric acid caustic solution was added to the burns, and the resulting mixture was at 4 hours 70 to 80 ° C in the presence of air.

B. A caustic solution with 5% Fe, (S04) 3 and 1% sulfuric acid was used added to the burns, and the resulting mixture was 4 hours at 70 bis 80 ° C in the presence of air.

C. An ammoniacal ammonium carbonate leach solution with 120 g / 1 NH3 and 90 g / 1 CO, as well as 10 g potassium persulfate (200 ml of solution each) was added to the burn-offs given, and the resulting mixture was stirred for 4 hours in the presence of air.

D. A 2% sulfuric acid leach solution only contains 10 g of potassium persulfate (each 200 ml of solution) was added to the burns, and the resulting mixture was Stirred for 8 hours at 75 ° C. in the presence of air.

E. An ammoniacal ammonium carbonate leach solution with 125 g / 1 NH3 and 111 g / 1 CO, was added to the burn-offs and the resulting mixture was Stirred for 8 hours at room temperature in the presence of air.

F. The caustic solution of method E was added to the burns, and the resulting mixture was 8 hours at room temperature in the presence of air rolled or shaken.

G. The caustic solution from method E, which contains 10 g of potassium persulfate (200 ml) were added, was added to the burn-offs, and the resulting mixture was rolled or shaken for 8 hours at room temperature.

H. A cupric ammonium carbonate liquor solution containing 60 g / 1 Cu; 120 g / 1 NH3 and 90 g / CO, was added to the burn-offs and the resulting mixture was Stirred in air for 2 hours at room temperature. Then the burns were filtered and with an ammoniacal ammonium carbonate leach solution (120 g / l NH3 and 90 g / l CO,) stirred for 2 hours at room temperature in the presence of air.

1. The same operation as method H, but the second mixture of Burnup and ammonium carbonate leach solution was in the presence for 4 hours at room temperature stirred by air.

J. An ammoniacal ammonium carbonate liquor solution (120 g / 1 NH3 and 90 g / 1 CO ") was added to the burns, and the resulting mixture was worked through for 16 hours at room temperature in the presence of air. Table 1 working conditions Example duration Average average speed or similar No. in hours of air supply Pyrite supply in the reaction space / o air of theory '" Nm3ih`: `kg / h, cm / sec. 1 13.0 31.36 14.35 46 97.7 2 4.0 31.23 13.88 46 100.6 3 3.5 30.12 13.32 44 101.1 4 48.0 31.43 13.89 46 101.3 5 48.0 31.21 14.05 46 99.4 6 48.0 25.07 11.03 37 101.7 7 48.0 31.14 14.34 46 97.2 @ 'Normal cubic meter per hour, given under standard conditions of 0 ° C and 1 atm pressure. '`` Theoretical amount of air is the amount that is required to convert all of the iron in pyrites to magnetite, Fe304 and to oxidize all the sulphide sulfur to sulfur dioxide. Table 1I Product analysis Example burn-up to ° / o S2% Cu ° / o Cu used No. Pyrite ratio in the burnup in the burnup ° / a SO = in roasting gases in the leached burnup leaching method 1 0.54 1.60 0.33 1.39 0.09 C. 2 0.55 0.82 0.28 12.8 to 13.5 0.08 A. 0.06 B 0.09 C 3 0.61 0.76 0.36 0.09 C. 4 0.51 0.34 0.34 13.1 to 13.9 0.08 A. 0.07 B 0.07 C 0.08 H. 0.07 I. 0.06 J 5 0.60 0.79 0.31 15.5 to 16.3 0.066 D. 6 0.62 0.22 0.28 15.7 to 16.2 0.047 A. 0.080 E 0.051 F. 0., 081 G 7th 0.62 1.46 0.28 15.7 to 16.0 0.083 G. EXAMPLE 8 The working conditions given in Table III below were applied to a fluidized bed of iron pyrite with 44.81 / o iron, 50.0% sulfide sulfur and 0.25% copper. The analysis of the starting gas and the values of the solids distribution can also be found in Table III. Table III working conditions Fluidized bed temperature, ° C ............ 800 Feed rate, g / min. .......... 26.2 Air velocity, Ncm3 / sec. ......... 987 % Air of theory * .................. 100 Speed in the reaction space, cm / sec. 46.33 Fluidized bed depth, cm .................. 76.2 Outlet gas analysis, volume percentage S0, ................................ 16.5 02 -................................. 0.0 Distribution of the solid product Reactor overflow g.'100 g feed ................. 30.2 Weight percent of the total product. . 45.2 Cyclone underflow g11100 g feed ................. 27.8 Weight percent of the total product. . 41.7 Anthers g / 100 g feed ................. 8.8 Weight percent of the total product. . 13.1 Total product, g, '100 g feed ..... 66.8 * Theoretical air volume = air volume required for oxy- dation of all of the Fe to Fe304 and of the whole sulphide sulfur is required to make S02. Chemical analyzes of the feed and reactor products can be found in Table IV: Table IV Chemical analysis of feed and reactor products Fe Cu total sulfur 1 sulphate sulfur 1 sulphide sulfur Pyrite feed ................... 44.8 0.25 50.2 0.2 50.0 Reactor overflow * '@ ` ................ 63.2 0.37 0.21 0.06 0.15 Cyclone underflow ** ................ 66.5 0.41 0.33 0.11 0.22 Dust bag ** ..................... 61.9 0.46 1.9 1.8 0.10 -xo / o sulphide sulfur as the difference between total sulfur and sulphate sulfur. In the case of a properly designed test that was carried out after preliminary tests. The burn-offs from the overflow from the cyclone and from the bag downstream of it were leached with a solution containing 5% ferric phosphate, Fe2 (SO @ 3 and 1% sulfuric acid, for 4 hours at 70 ° C. The copper and iron analyzes of the burn-off were found in the following table: Table V Chemical analysis of leach residues Cu Fe Overflow leach residue ....... 0.10 64.1 Cyclone leach residue ........ 0.06 67.7 Bag leach residue ......... 0.09 65.0 Calculated composition Leach residue * .......... 0.08 65.7 * The calculated composition is based on the weight ratio of formal products from the roasting experiments. An ammoniacal ammonium carbonate leach was applied to an unleached composite burnup containing 0.39% copper and consisting of 52 parts overflow burnup and 48 parts cyclone burnup. The aqueous long solution contained 95.2 g / l NH3 and 98.5 g / l CO 2 and was brought into contact with the burnup in a ratio of 100 parts by weight of burnup to 500 parts by volume of long solution for 24 hours at room temperature in an open reaction vessel. The leached combustion contained 61.3% iron, 0.1% copper and 0.09% sulfur. Example 9 The operating conditions in Table VI below were applied to a fluidized bed of iron pyrite containing 50.0% sulfide sulfur. Sulfur dioxide in the exhaust gas, the sulphide sulfur content of this burn-up and the copper content in the leached burn-up can also be found in the table. Leaching was carried out in a similar manner to Example 8 using an aqueous solution containing 5% ferric sulfate and 1% sulfuric acid. Table VI Temperature, ° C ....................... 800 Working time in hours ................ 4 Feed rate, g / min. ..... 26.0 Air velocity, Ncm3 / sec. ......... 940 Speed in the reaction space, cm / sec. 43 % Air of theory .................... 95 % SO, in the outlet gas ................. 15.6 % S = - S in overflow ........................ 0.66 in the cyclone .......................... 0.72 % Cu in the leached combustion Reactor overflow .................... 0.10 Cyclone underflow .................... 0.08

Claims (7)

PATENT CLAIMS: 1. Process for roasting iron sulfide materials, those with one or more non-ferrous metal substances, such as copper, nickel and cobalt, are contaminated, for the purpose of producing sulfur dioxide suitable for the production of sulfuric acid and iron oxide-containing burnouts, which reduce the content of non-ferrous metal substances let it leach, preferably with the simultaneous dissipation of usable heat from the Process, characterized in that the sulfide with oxygen in such Quantitative proportions and under such conditions brings about implementation that a gas phase forms which sulfur dioxide is essentially free of sulfur trioxide has, and a solid phase, which a burn-up in the form of Magnetft substantially contains free of ferric oxide, forms, separates the two phases produced and cool the magnet under non-oxidizing conditions. 2. Procedure according to Claim 1, characterized in that the reaction is carried out by feeding in the sulfide takes place in finely divided form in a fluidized bed, which by passing a Oxygen-containing gas is flowed up. 3. The method according to any one of the claims 1 and 2, characterized in that the sulfide at a temperature in the range from about 700 to at most 900 ° C, preferably about 800 ° C, with an amount of oxygen is converted, the 94 to 1031) / o, preferably about 101%, of the amount of oxygen which corresponds theoretically for the oxidation of the total sulphide sulfur content the sulphide to sulfur dioxide and the total iron content of the sulphide to magnetft is theoretically required. 4. The method of claim 1 or 2 for roasting Iron sulfide, which is contaminated with a copper compound, in addition to the sulfur dioxide to produce a magnetic burnout that is practically free of iron oxide and copper impurities and is suitable for iron or steel production, characterized in that the Sulphide at a temperature in the range between about 700 and less than 900 ° C, preferably at about 800 ° C, with an amount of oxygen corresponding to 94 to 103 %, preferably about 101% of the amount of oxygen theoretically required to oxidize the total sulphide sulfur content of sulphide to sulfur dioxide and the whole Iron content of the sulphide is required to Magnetft, implemented and the burnup is leached to reduce the copper content to the desired amount. 5. Method according to one of Claims 1 to 4, characterized in that the burn-up is leached with an acidic ferric sulfate liquor solution in the presence of air. 6th Method according to one of Claims 1 to 4, characterized in that the burn-up with a dilute aqueous solution of ferric sulfate and sulfuric acid in the presence is leached by air. 7. The method according to any one of claims 1 to 4, characterized characterized in that the burn-up with an aqueous ammoniacal ammonium carbonate solution is leached in the presence of air. Publications considered: German Interpretation document No. 1116 251.