FI63967B - FOERFARANDE FOER BEHANDLING AV SULFIDISKA ORENA KOPPARBEMAENGDA KOMPLEXMALMER OCH -KONCENTRAT - Google Patents

Description

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This invention relates to a process for the treatment of sulphide impure copper-dominated complex ores and concentrates by perforation known per se, and in particular to a process for the treatment of endings / concentrates of such ores or concentrates. The process according to the invention is thus particularly suitable for impure copper-dominated complex ores and concentrates, such as Fahlerzit and various enargite-type complex ores, for which the structural sulphidation to be carried out is endothermic.

The complex ores and concentrates to be treated according to the invention contain copper and iron as the main components, and often also nickel, cobalt, zinc and other metals. The components are generally bound to complex sulfides containing arsenic, anti-many, bismuth, selenium and tellurium. Due to the origin of the ores, the ores quite often contain rare and valuable heavy metals. High-order, heavy and volatile impurity metals are present in ore mineral foundations generated at low temperatures and pressures. The ores covered by the process thus occur mainly in connection with pegmatite-distal-pneumatolytic and especially hydrothermal rock and ore formations. In this case, the impurity elements are either as trace elements in the lattices of the main metal sulphides or directly as structural components in the complex complex minerals. Naturally, many impure metal and metal compound precipitates and powders generated as a by-product of the metallurgical industry are also covered by the process.

Structural change sulfidation is known per se e.g. FI patent 56 196. In it, the complex structures containing ore or concentrate impurity metal are decomposed by sulfidation, whereby both the main and the impurity metal form simple and stable sulfides. Method The partial pressure and temperature ranges of sulfur are ρ „= 0.2-1.0 atm and T = 600-900 ° C. The method uses preheated concentrate, sulfur vapor and indirect heating of the equipment if necessary. Depending on the temperature and the amounts of substances, some of the impurity components evaporate according to their vapor pressures, in whole or in part, as sulphides, compounds or alone.

The structural sulphidation known from FI patent 56 196 has been used as part of e.g. In F1 patents 57,090 and 58,353 in known methods for treating complex ores and concentrates.

The process according to FI patent 57,090 utilizes the dissociation recombination energies of sulfur vapor molecules in the control of the sulfation process, which are quite high in the applicable low temperature range and high sulfur vapor partial pressure. Often in sulfidation processes, the amounts of energy produced or bound by sulfur vapor are sufficient, so the oxidation fed from outside the process! no electrical energy is required. In the process according to FI patent 58,353, the evaporation of impurity metals in addition to the structural sulphidation of minerals is enhanced by converting volatile sulphides or metals into stable halides into the gas space. At the same time, the heat amounts of the sulfidation process can be controlled because the formation of halides is an exothermic process that releases large amounts of energy.

In the above-mentioned methods known per se, no fossil fuels have been used in the reaction space in the actual sulfidation system.

Known methods for sulfiding concentrates and ores comparable to the above methods use both direct and indirect heat transfer to implement process temperature balances. When processing 3,63967 concentrate or ore powders in the solid state, drum furnaces and mechanical layer furnace equipment are commonly used as reduction and sulfidation equipment. When the heat transfer is indirect, the equipment can be chosen more freely. Let us consider some known methods from both groups.

In the process of U.S. Patent 3,459,535, chalcopyrite and bornite are converted to a number of simple sulfides in the presence of elemental sulfur at a temperature in the range of 300-600 ° C. On the basis of current knowledge, covellite, idaite and pyrite are formed under these conditions. The resulting new structure is more advantageous than the old when using oxidative acid pressure leaching to sulphide copper leaching. The method is carried out as a single process in a retort, where finely divided sulphides and elemental sulfur are indirectly heated.

In the sulphidation process according to U.S. Pat. No. 3,817,743, the conversion of chalcopyrite to X-bornite and idolite is mainly carried out at a partial pressure of elemental sulfur vapor r ≤ 2 = 0.25 to 1.00 atm and in the temperature range 400 to 500 ° C. Copper is easier to dissolve from the product sulphide than the original. The method is carried out in a Herreshoff-type bed with an indirect heating. Nitrogen is used as the carrier gas for sulfur vapor.

In the process of U.S. Patent 2,059,421, zinc vapor is sulfided with elemental sulfur to form a zinc sulfide pigment, which is separated from the inert carrier gas of the starting materials after fines. The process is carried out in a reaction tube to which the starting materials are fed solid, molten or gaseous. The sulfidation reaction is so exothermic that no external heat transfer to the system is required.

In its development, the evaporation method, which is still at the turn of the century and is based on direct heat transfer and is still in use today, is the so-called Wälz process (e.g. V. Tafel: Lehrbuch der Metallhiittenkunde, Leipzig 1929, 154, 444, 458-463). The method is carried out in a rotary drum oven.

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Approximately 50% by weight of escort and combustion coke are mixed into the batch consisting of slags, oxides, sulfides, air dusts, etc. (after processing, escort coke, which is difficult to remove from waste oxides, is still about 20-40% by weight of the batch weight). Evaporation is based partly on conversion reactions and partly on metallic evaporation (Zn, Cd, Pb, Cu, Ga, Ce, As, etc.). The evaporation is usually oxidized in the oxidizing gas phase above the mattress, the gases and evaporative oxides are cooled and recovered from the piping and dust bags.

Analogous to the Wälz process, mainly sulfide evaporation in a drum furnace (flame and bed furnaces are also suitable) as a countercurrent process is used in the impurity evaporation process of U.S. Patent 1,762,867.

Also present are the Herreshoff and Lurgi type kiln processes currently used for direct heat transfer, often operating under low oxygen pressure and partially roasting sulfide ore. Often impurities are allowed to oxidize in the system. Evaporation and gases are often cooled in mechanical kiln equipment and recovered by filters. Partial roasting in suspension, a fluidbed system, cooling of the gas phase with water and a hot and cold electrostatic precipitator for the selective separation of condensates are also used. At the same time, a number of process arrangements using direct and indirect heating of the reaction mass and space (as well as the intermediate forms of the above) have been presented. Of these, mention may be made of the complex furnace-bound shaft furnace process according to Swedish patent 64,726, in which arsenic is evaporated from copper, sulfur, magnetic and arsenic ores as di- or tri-sulfides. The sulfur deficiency of the charge is used by pyrite addition. Evaporation of arsenic compounds takes place by heating the feed mixture both directly and indirectly with the aid of neutral, tempered fuel gases. Combustion gases are produced in a two-part unit · In the second part of the unit, coal is coking and the resulting reducing gases are used for preheating the ore (at the top of the furnace unit). In the second part of the apparatus, the coke is burned as a neutral fuel gas, whereby the actual evaporation is carried out transversely to the shaft furnace by means of channels built horizontally through the mattress. Mechanical scraping systems take care of the movement of the concentrate mattress. In the process according to Swedish patent 85,624, the evaporation of arsenic and sulfur from the concentrate mattress is carried out in a hermetically sealed shaft furnace at its feed end. Neutral gases rising from the melting zone are reduced by the downward flow of mattress carbon and preheat the concentrate mattress (copper, sulfur and arsenic pyrite), whereby pyritic sulfur separates and arsenic evaporates as a gas. Some of the arsenic evaporates and some is oxidized in the melting zone to oxide, which is reduced from the gas phase by mattress carbon to metal in the evaporation zone. The behavior of arsenic is thus similar to the previous process - Swedish patent 64726 A similar sulfide - pyrite additive - evaporation process for arsenic and sulfur is a process according to Swedish patent 66 711 in the context of electric furnace melting.

As an intermediate form of heat supply, a broad process according to U.S. Pat. No. 3,313,601, in which the reaction mixture of natural gas and sulfur dioxide is sulphated in a fixed reactor, the oxide, sulphide, arsenide, selenide, complex oxide and sulphide mattress metals (including Cu, Pb, Zn, Cd,

Sb, Sn, Si, Ni, Co, Mn, Acj, Ge, Cu, Mo, V, Ga, Pe, U, Ti,

Ta, Nb, Cr). The reactor can be heated by direct combustion of natural gas in the reactor space or by an indirect method.

The process according to the invention is thus intended to improve the temperature balance in the treatment of impure copper-dominated complex ores and concentrates for which the structural sulphidation to be carried out is endothermic, and the essential features of the invention appear from the appended claim 1.

_ - 1 ..

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The invention will be described in more detail below with reference to the accompanying drawings, in which Figure 1 shows the P-T equilibrium states of Cu, Fe, As, Sb and Bi and Figure 2 shows a side view of the apparatus used to carry out the method according to the invention.

In the process according to the invention, the structural change sulphidation of the minerals of the concentrate or ore powder and the simultaneous evaporation of the impurity components are carried out in a solid state and at a high partial pressure of elemental sulfur. The simultaneous use of coal and sulfur as an additional fuel in the processing of concentrates with an overall endothermic process is essential for the process. According to the invention, the carbon is converted into disulfide by means of steam of elemental sulfur, which is then oxidized. The process according to the invention has succeeded in oxidizing the converted carbon at an unusually low temperature and oxygen pressure and in such a way that the oxides of the impurity components are not exceeded or the dissociation pressures of these sulphides are exceeded in the gas phase. In the method according to the invention, carbon oxidation is thus provided outside the concentrate bed to be quantitatively sulphidated, whereby the concentrate bed does not significantly overheat. Such a combustion method is particularly suitable for processing complex minerals of the Fahlerzi or enargite type, which tend to melt before the complexes decompose due to sulfidation.

The sulfidation process according to the invention is based on e.g. to the following observations: - In the reaction space, sulfur carbon is generated from elemental sulfur vapor and e.g. from the carbon fed with the concentrate or ore bed, which can be oxidized as a gaseous material outside the reaction bed. In this case, due to the suitable calorific value of the conversion fuel and the oxidation site, no areas of local overheating leading to melting or sintering of the complexes are formed.

7 63967 - The conversion fuel can be completely oxidized without disturbing the cracking phenomena, at low temperature and in the low product gas phase to oxygen partial pressure.

- The amount of carbon in the additional fuel can be limited so that kinetically advantageous oxidation is achieved and also the amount of harmful by-products of the gas phase obtained as a product is minimized.

- The auxiliary fuel can be oxidized so that the oxygen pressure in the gas phase falls below and the sulfur pressure exceeds the corresponding dissociation pressures of the pollutant oxides and sulphides. The oxidation can also be carried out in such a way that, in addition to the high sulfur-vapor partial pressure, sulfur and carbon dioxide are predominant in the product gas phase. In this case, regardless of the limited amounts of fuel and oxidation conditions, sufficient amounts of heat for processing are achieved.

- The use of carbon in addition to sulfur as an additional fuel causes an increase in the elemental sulfur partial pressure of the product gas phase and thus allows a high sulfur content of the impurity polymer condensing from the gas phase, which homogenises the polymer and ensures its insolubility in concentrated solutions.

- The natural or added iron content of the concentrates has a very advantageous effect on the structural change sulphidation of copper-dominated minerals. The chalcopyrite and / or bornite equilibrium resulting from the iron phase in the product phase reduces the endothermicity of sulphidation, the required sulfur vapor partial pressure as well as the impurity residue compared to non-ferrous digenite equilibria (digenites require e.g.

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The very high harmfulness of the impurity components, arsenic, antimony and bismuth in e.g. pyrometallurgical metal processing methods is generally known. Some of the heavy trace element components (eg mercury, cadmium, tellurium, thallium), which contain highly toxic substances, are a major detrimental factor for nature conservation. A large proportion of trace elements are also of high order in the periodic table, and thus the trace components as rare substances are very valuable both technically and economically. According to the invention, the rare substances can be enriched in a sulfur polymer, from which they can be advantageously recovered.

The rationale for the process of the invention can best be described by briefly examining the behavior of some complex copper minerals during structural change sulfidation. The most important group of ore minerals within the scope of the invention is a large series of Fahlerzians, which in aggregate form the general form (Cu, Ag) 12 (Cu, Ag, Fe, Hg, Ge, Sn) 12 (As, Sb, Bi) gS26.

The known copper fahlerzi is the mineral tennantite of the Cu-As-S basic system, Cu24ASgS2g.

More important than Fahlerz is another important series of copper minerals, i.e. the enargite series, whose mineral in the basic system Cu-As-S is the enargite, Cu24 (As, Sb) gS32.

The reaction equation combining said pure minerals is 8. 2/3 Cu12As4S13 (s) + S2 (g) <p = ± 8/3 Cu3AsS4 (s) 8.1 LogPo = 9072 T-1 + 7.634 ö2

Tennantite melts at 665 ° C with Cu12, 31Ab4 ^ 13 * The stoichiometric enargite decomposes into arsenic-poor enargite, Cu3AsQ Q4S4 'liquid at 660 ° C. However, the Cu-As-S system has not been studied under controlled sulfur pressure, so the melt phase ranges and melting temperatures corresponding to the above-mentioned 9,63967 and other possible reactions may differ from the values mentioned for low sulfur pressure. In the stability plot, Figure 1, the tennantite-enargite balance is denoted by the number 8.

At high elemental sulfur partial pressure, the enargite reacts with elemental sulfur corresponding to reaction equation (9) (Fig. 1), i.e. 9. (2-6) Cu3AsS ^ (1, s) f = * 3Cu2_gS (s) + (1-δ / 2) As2S3 ( s, 1.1 g) + (1-56 / 4) S2 (g)

The equilibrium pressure corresponding to the degradation of enargite (As2S3 (l)) is 9.1 logPs = -9201T-1 + 9.926 logT - 21.904 2

For the digenite obtained as a reaction product, the equilibrium reactions are as follows: 1. (1-6 / 2) Cu2S (ss) + (6/2) S (ss) - + Cu2 ^ S (ss) 1.1 aCu2s = "2 <5" 203.7T_1 + 1.3222 1.2 (6/4) logP ^ = -1603.8T_1 - 2.6908 logT + 9.5353 - (1-6 / 2) logaru g At a temperature of 1000 ° K, equations for the equilibrium state of digenite are obtained e.g. values (2 ~ δ / αCu g / Pg): 1.835 / 0.778 / 9.46xK> "2} 1.803 / 0.719 / 4.56x1ο" 1 and 1, ^ 92/0 ^ 695 / 8.36x10-1.

At a temperature of 1000 ° K is the value of the free energy of the ground state reaction (9), AG ° = +6065 cal per mol As2S3 (l). Because Cu2S activity is low at high sulfur pressure in digenite, the reaction proceeds despite the positivity of free energy. When operating at high sulfur pressure, no melting phenomena were experimentally observed as the reaction (9) proceeded.

The equilibrium obtained by calculating the thermodynamic (inaccurate) values (9) shows that a relatively low partial pressure of elemental sulfur -2 -1, i.e. at a temperature of 1000K: 10 <ps ^ <10 atm, is required when calling the conductor enargite. However, in low sulfur partial pressures, melting and sintering phenomena are expected in the product-feed system in the region of the boiling point of arsenic trisulfide. In addition to eliminating the effect of arsenic and sulfur defect, which correspond to the melting point combinations of minerals, the use of elevated sulfur pressure plays an important role in significantly increasing the reaction rate. As the sulfur content of the digenite in the product concentrate increases, the content of arsenic remaining in the product decreases. Thus, it is not advantageous to reduce the partial pressure of sulfur vapor when performing enargite-digenite conversion.

When developing the restructuring sulfidation method suitable for copper complex concentrates, it was found that harmful melting and sintering phenomena occurred quite rarely in lattice-containing iron Fahlers and also in tennantite and enargite containing independent iron sulfide and / or thioarsenide minerals. In this case, it could also be found experimentally that the sulphation of the mineral matrices and the evaporation of the impurities could be carried out at a lower than usual sulfur vapor partial pressure without significantly reducing the reaction rate and without increasing the arsenic residue of the product concentrate. The partial pressure of sulfur vapor must not, of course, fall below the dissociation pressures of the impurity sulphides, especially when evaporation as sulphides is most advantageous (normal situation).

The sulfidation and evaporation processes of Fahlerz and enargite-type concentrates are almost always so strongly endothermic that conventional preheating of elemental sulfur vapor and concentrate is not sufficient to meet the thermal balance of the system. Additional heat must thus be generated in the system by either indirect or direct heat transfer to the reaction space. The ability to process the concentrate using a lower than usual sulfur vapor partial pressure allows oxidation of the fuel in the reaction space. It must be possible to oxidize any additional fuels, approximately 63967 sulfur and carbon, so that no additional local heat is generated (ie the risk of melting of complex minerals is avoided). The oxidation must also be successful under conditions where a very low oxygen pressure below the dissociation pressures of the pollutants is present and at the same time where the sulfur vapor pressure exceeds the dissociation pressures of the impurity sulfides.

When the product phase is chalcopyrite or bornite, the following equations for the sulphidation of enargite are obtained by feeding stoichiometric pyrrotite 2 2Cu3AsS4 (s) + 6FeS (s) + I / 2S2 (g) ¢ = ½ 6CuFeS2 (s) + AS2S ^ (1)

2.1 AG = -139780 - 233.717TlogT + 818.330T

3 5Cu3AsS4 (s) + 3FeS (s) ^ => 3Cu5FeS4 (s) + 2 l / 2As2S3 (1) + 13 / 4S2 (g)

3.1 AG = 24785 - 113,480TlogT + 3Q1., 254T

At a temperature of 1000 ° K, the value of free energy per mole of arsenic trisulfide is obtained by the chalcopyrite reaction AG = -22600 and by the bornite reaction, AG = -5760 cal. It can be stated that the above-mentioned reactions in the presence of both pyrrotite and pyrite are thus more advantageous in terms of equilibrium than the digenite reaction (9).

Consider the heat demand of conversion reactions. The comparative reactions are as follows: 4 2Cu3AsS4 (s) + 6FeS (s) + 1 / 2S2 (g) ψ = * 6CuFeS2 (s) + 1 / 2As4S6 (g) 5 2Cu3AsS4 (s) + 6FeS (s) + 1 / 2S2 (g) * = * 3Cu2S (s) + 6FeS (s) + 1 / 2As4S6 (g) + I S2 (g) 6 2Cu3AsS4 (s) <== ► 3CU2S (s) + 1 / 2As4S ^ (g) + S2 (g) 7 5Cu3AsS4 (s) + 3FeS (s) e = li'3Cu5FeS4 (s) + As4S6 (g) + I s2 «J> 12 63967

In reactions (4) and (5) per ton of enargite is obtained as a feed balance - Mcal - 4.1 ÄHe + f = 204.635x10 ~ 3T + 21.300x10_6T2-349.508 + 40.711x10 3Ahs ^, where the enthalpy of sulfur vapor is 4.2 logAHSx = "159.568 + 184.577 69.002x10 ~ 6T2 + 46727T-1

According to reaction (4), the reaction results in the conversion of chalcopyrite, which in reaction 5 is hypothetically omitted. The product balances are: 4.3 AHe + f = 289,830x10 ~ 3T + 2, Ol5x10 ~ 6T2 - 392,356 5.1 ΔΗ = 212,851x10 ~ 3T + 11,080x10 ~ 6T2 - 305,345 + e + r 122,183χ10_ · 5ΔΗς * x

Assuming a feed temperature of 773 ° K for enargite and pyrrotite and a temperature of 1000 ° K for sulfur vapor and products, the temperature requirement for reactions (4) and (5) is 56.0 and 141.3 Mcal, respectively. The formation of chalcopyrite thus reduces the endothermic reactions of iron and sulfur binding. In the enargite-digenite (here as chalcosite) conversion, the feed and product balances per ton of enargite are as follows: 6.1 AHg + f = 111.694x10_3T + 12.235x10 ~ 6T2 - 150,196 and 6.2 ΔΗ = 119.910x10 ~ 3T + 2.015x10.06 +2T2 + 106.0 81.422x10 ~ JAHg x

As a balance difference, the temperature requirement of reaction (6) is 116.6 Mcal, i.e. reaction (6) is much more endothermic than reaction (4).

In the enargite-bornite conversion according to reaction (7), the difference between the feed and product balances (temperatures and T ^) gives the temperature balance i3 639 67 ΔΔΗθ + £ = 166,579χ10_3Τ2 - 130,282χ10_3Τ1 + 2,015χ10_6Τ ^ -14,048χ10 ~ 6Τ - 7,254 + 56.994 3Δη8 χ 'χ = 83,130, which is the value between reaction temperatures (4) and (6).

It should be noted that the examined balance sheets lack e.g. heat losses of the performance equipment, etc., so the heat demand of the reaction-based processes is higher than mentioned.

The sulfidation of the enargite concentrate follows the kinetic approximation of equation 10. 1 - (1-x) 1/3 = / k (t-to) / 1/2 where x is the ratio of the change in instantaneous and maximum weight of the sample, t is time - min - and k is the reaction rate constant .

When the concentration (% by weight) of the concentrate is 27 Cu, 15 Fe, 10 As and 30 S, the reaction rate constant is 10.1kl / 2 = 3660 exp (-20110 / RT)

As the concentrate becomes more pyritic in size, i.e., 26 Cu, 14 Fe, 10 As, and 34 S, the reaction rate constant increases by about 16%. Thus, a slight increase in the elemental sulfur content of the atmosphere increases the partial pressure of the sulfur vapor and at the same time the reaction rate. However, when chalcopyrite and / or bornite is obtained as the end product of sulphidation, the stability of which requires relatively low equilibrium pressures of sulfur vapor, there is no reason to reduce the partial pressure of sulfur vapor in the system to a range of technically unfavorable reaction rates. On the other hand, the conversion and evaporation reactions are endothermic to the overall process, so additional heat must be fed into the system. The cheapest way to produce additional heat is direct oxidation of elemental sulfur and / or e.g. fossil fuel in the reaction space. In direct oxidation, the partial pressure of sulfur vapor decreases at least corresponding to the volume of the combustion gases and the side reactions.

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Oxidation of elemental sulfur vapor to obtain additional heat is generally not advantageous due to its low calorific value, especially when the amount of heat required is high (oxidation of sulfur vapor with oxygen at a reaction temperature of 1000 ° K produces heat of 3.145 Mcal / kg). The use of coal or a similar fossil fuel is difficult because the high temperature generated locally easily leads to the melting of the complex mineral before it is sulfided. Oxidation of fossil fuel to the required low oxygen pressure may also be incomplete due to cracking.

According to the invention, the carbon powder is mixed with the concentrate and fed to the furnace, where it reacts with elemental sulfur fed to the furnace as a gas (or otherwise) and also from the batch conversion reactions to form a furnace reaction space in the gas phase above the mattress. This can then be oxidized (with oxidation reaction oxygen at 1000 ° K to produce 3.847 Mcal / kg CS 2) at the desired point in the reaction furnace space. Because combustion takes place in a controlled and completely gas space outside the mattress, there is no local risk of the concentrate mattress overheating. It is clear that sulfur-carbon can also be produced outside the furnace device. Likewise, the carbon can be fed as one or more suspensions from outside the furnace to a reaction space containing elemental sulfur vapor and feed concentrate. Experimentally, it was found that the conversion of carbon disulphide and its oxidation are technically sufficient in speed. The oxidation can also be easily carried out close to equilibrium and in such a way that in the product gas phase the impurity sulphides (or partly the metals) remain stable and the oxides unstable.

Expressed per unit activity, the dissociation pressures (Pq ^, atm) of the pollutants oxides in the operating range of the method are as follows:

As203: LogP0 = -23260T_1-0,101 LogT + 7,697

Sb-07: LogP0 = -24290T_1-2,8871ogT + 17.741 ^ 0 2 15 63967

Bi «0_: logP0 = -20600T_1-2.7201ogT + 18.413 z j 2

SeO_: logP0 = -10370 ^ -0, 9061ogT + 7.282 ^ -1

TeCL ·: logP0 = -17410T -1, 360logT + 14.192 Z -1

HgO: logPO = -15788T + 0.6041ogT + 20.556

2 -1508x10 ~ 3T

The best carbon-converted carbon is charcoal (or peat coke), but various fossil carbons and hydrocarbons are also suitable. However, the use of the latter requires a flue gas cleaning process due to hydrogen side effects, which is technically demanding.

The equilibrium states, mass and temperature balances of the method according to the invention have been considered by means of application examples. In these, the essential functions of the method have been studied with respect to the main variables. Of course, not all possible method variations can be considered in this context. In the experimental runs corresponding to the examples, an iron-containing enargite-type concentrate has been used, the essential impurity components of which, in terms of the copper of the main component, were the elements Zn, Pb, As, Sb, Bi, Se, Te, Hg, Ag and Au.

In the application examples, e.g. the following functions: - Use of conventional and oxygen-rich (50%) air as an oxidant.

- Use of elastic sulfur as an additional fuel.

- Simultaneous use of elemental sulfur and coal as a supplementary fuel; when the sulfur vapor feed rate was constant (29.1 kg), the carbon feed rate varied (10.0, 13.5, and 17.0 kg per ton of concentrate).

- Effect of gas phase oxygen pressure on gas phase composition and temperature balance when operating in the range of dissociation pressure of arsenic trioxide (P0 = 1-4x10 ^ atm).

2 ie 639 67 - Variation of the sulfur pressure of the gas phase as a function of carbon content, oxidant and oxygen pressure in the range, Pg = 0.1-0.3 atm. The sulfur pressure range was abundant above the dissociation pressure of arsenic ε-risulfide to achieve a sufficient reaction rate.

- Variation of the sulfur content (53-58% by weight S) of the sulfur polymer containing impurity elements as a function of gas peeling.

- The effect of the amount of carbon on achieving a low oxygen pressure limit and a sufficient reaction rate, as well as the ability to generate sufficient heat in addition to process heat to cover heat losses depending on the technology used (without contamination of the product gas phase with COS, CS2 H2S, etc.).

Experiments for the practical implementation of the method according to the invention were carried out with the pilot conversion apparatus according to Figure 2. This consisted of an indirectly heated drum furnace 1 acting as a sulphidation device, a sulfur evaporator 2, a preheating and dissociating device for the feed steam 3, a preheating of the carrier nitrogen 4 6, a sulfided product concentrate discharge device 8, a product gas phase removal 9 and a product sulfur polymer removal device 10.

The equipment was hermetically sealed and, if necessary, fully automatic. The magnitude of the heat loss of the sulfidation-drum furnace 1 could be adjusted, if necessary, by adjusting the electric power supply of the furnace.

eXAMPLES

Enargite-type test dew has been used in the experiments. Arsenic and antimony occur interchangeably in the enargite lattice. Mercury and precious metals are in the form of selenides and tellurides. Zinc is bound and lead as an independent sulfide. Iron occurs in a partially independent pyrite-pyrrotite mixture.

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The elemental analyzes of the feed concentrate and products are indicated in Table 1. The composition of the oxide phase (Table: Ox) with the feed concentrate (wt%) was as follows: 2.30 S1O2 / 0.57 A ^ O ^ / 0.22 CaO, 0.03 MgO and 0.10 TiO2. The notation Me indicates the low total content of the metals Sn, Ni, Co, Mn and Cd. The approximate mineral analysis calculated from the analysis of the feed and product concentrates is shown in Table 2. The metals in the polymer portion of the product-gas phase are shown as sulfides to facilitate consideration, although it is not mineralized.

The feed concentrate contained enough iron to create a chalcopyrite-bornite balance in the product concentrate, so there are no significant variations in the sulfur content in the products due to changes in the sulfur potential of the gas phase. For this reason, the same composition of metal sulphides of the product concentrate and the polymer part has been used in the balance sheet calculations in all cases corresponding to the eight balance sheets of the example. The material and temperature balances of the example as well as the material balances and analyzes of the gas phases are given in Tables 3 and 4.

The series of experiments were performed at oxygen and sulfur pressures below the dissociation pressure of arsenic trioxide and above the dissociation pressure of trisulfide, respectively. In the case corresponding to Sub-Example I, the fuel was oxidized with air and in other cases with oxygen-enriched (about 50% by weight O2) air. Except for the case corresponding to Sub-Example VIII, where no carbon was added as an additional fuel, the same amount of elemental sulfur feed, i.e. 29.1 kg per ton of feed concentrate, was always used in the different test periods. The amount of carbon input in the experimental periods corresponding to the sub-examples was as follows (kg / example): 17.0 kg / I-III, 13.5 kg / IV and 10.0 kg / V-VII. Powdered charcoal has been used in the sub-examples considered.

From the values in Tables 3 and 4, it can be seen that when the supplemental fuel supply is constant, the amount of heat from the system is an almost linear function of the oxygen pressure in the product gas phase.

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On the other hand, in the studied region, the amount of additional fuel delivered at constant oxygen pressure has an approximately linear function of the amount of heat obtained.

The heat loss corresponding to sub-example VIII in Table 3 is 20 Mcal per tonne of feed concentrate. This value already requires a very good oven device from a thermal engineering point of view. With an amount of feed carbon of 10 kg, the same heat loss is achieved with an oxygen pressure in the gas phase of “16

Pq = 2.3 x 10 atm corresponding. On the other hand, at a constant oxygen pressure, PQ = 10 atm, a carbon amount of 15 kg per tonne of feed concentrate is needed to compensate for said heat loss.

Feeding elemental sulfur into the system and at an early stage of processing (in similar process cases, elemental sulfur is fed into the system at the same time as the concentrate, the feed carbon was already mixed into the concentrate before feeding) is preferred to convert additional fuel to gaseous form - In this case, the distribution of energy in the oxidation of the fuel can be easily adjusted, for example, by selecting the combustion point.

Also, the partial pressure of the elemental sulfur may decrease, especially in the early stages of processing, without addition, in the presence of a large amount of carbon, too low for the decomposition and sulfidation reactions to take place. It should be noted that a sufficient amount of gas phase sulfur vapor is necessary, in addition to exceeding the dissociation pressures of gaseous impurity sulfides, also to keep the sulfur content of the impurity sulfide-containing polymer obtained in the condensation in the range of 50-60% by weight. In this case, the viscosity of the polymer is still low enough for easy handling. In cases corresponding to the sub-examples, the sulfur content of the polymer (% by weight S / example) is as follows: 57.3 / 1, 58.0 / 11, 56.0 / 111, 58.1 / IV, 58.2 / V, 56.4 / VI, 52.8 / VII and 58.1 / VIII.

19 63967

The examples show that in the process according to the invention the simultaneous control of both oxygen and sulfur pressures in the gas phase can be easily carried out. Said pressures can also be kept below the dissociation pressures of the oxides of the impurity strips and above the dissociation pressures of the corresponding sulfides. Carbon can be easily oxidized in the presence of elemental sulfur at low temperatures and so that local areas of overheating in the system do not develop. This is accomplished by allowing the carbon to gasify to carbon sulfide, which is burned outside the mattress with a suitable choice of oxidation-gas feed locations. In the pilot furnace used (short), oxidation was carried out at a distance of about 1.5 m (end) from the feed end of the furnace to the steel tube by means of a closed A 2 O 2 tube. On an industrial scale, the oxidizing gas can be fed, for example, when using a tubular furnace by means of radial feed pipes arranged along its side line. In the same way, both sulfur vapor and other gases can be fed into the system. The experimental examples also show that, in addition to the required process heat, amounts depending on the use of different furnace equipment can be fed into the system, if necessary, to cover the heat losses.

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Claims (2)

25 63967 1. A process for the treatment of sulphidic, orenic, complex-free complexes and concentrates in a structured and structural sulphidation process, the conversion of gas-formed colloidal oxides to a reaction temperature of 600-900 ° C to 0.1 ° C atm, which ligands ovanför föroreningssulfidernas dissosiations-tryck, och sä att deltrycket av syre ligger nedanför för-oreningsoxidernas dissosiationstryck. A process for treating sulphic impure copper-dominated complex ores and concentrates by a structural sulphidation process, characterized in that gaseous sulfur carbon is oxidized in a reaction space at 600-900 ° C at a partial sulfur pressure of 0.1-0.3 atm, which is above the dissociation pressures of impurity sulphides, that the partial pressure of oxygen is below the dissociation pressures of the pollutants. Process according to Claim 1, characterized in that the gaseous sulfur carbon to be oxidized is formed outside the reaction space and fed to the reaction space together with the elemental sulfur vapor. Process according to Claim 1 or 2, characterized in that the oxidizable gaseous sulfur carbon is formed in situ in the reaction space from carbon and sulfur. Process according to Claim 3, characterized in that the carbon required for the formation of gaseous sulfur carbon is fed as a powder together with the complex concentrate or ore fed to the reaction space. 2. For the purposes of paragraph 1, a reference to the oxidised form of the column is shown in Figure 2.