DE2451580A1 - Hydrometallurgical processing of copper pyrites - and copper-nickel concentrates or smelting residues or scrap by leaching with oxygen under pressure - Google Patents

Abstract

Hydrometallurgical processing of Cu pyrites- and Cu-Ni concentrates and residues, intermediate products and flue dusts of pyrometallurgical smelting of non-ferrous metal ores and their scrap, takes place by leaching the finely divided starting materials with O2 under press. Pyrite-contg. Cu- or Cu-Ni concentrate starting materials are leached without acid addn. and other starting materials with acid addn. at 160-200 degrees C, to set up a Cu content of soln. of 60 g/l. The free H2SO4 content set up is lowered to about 20 g l, either by (a) admixing press. leach soln. with matls which dissolve under H2SO4 consumption and which themselves contain no or only small quantities of S, or (b) by de-coppering the press. leach soln. by solvent exten., using the de-coppered soln. for leaching finely ground Cu- or Cu-Ni concentrates at ca 110 degrees C, de-coppering the soln. obtd by solvent extn. adn combining the 2 Cu-contg. solvent extracts Fe content of soln. is 4 g/l. Use of additional chemicals is small and is limited to NaOH and CaO.

Description

Process for hydrometallurgical processing of copper pyrites concentrates, Copper-nickel concentrates and residues, intermediate products and flue dust of the pyrometallurgical grinding of non-ferrous metal ores and their scrap waste The invention relates to a method for dydrometallurgical processing of copper pyrites concentrates, copper-nickel concentrates and residues, intermediate products and fly dust from pyrometallurgical smelting and non-ferrous metal ores and their scrap waste.

The leaching of sulphidic non-ferrous metal concentrates with oxygen in water under pressure at around 2000C has long been known (N.G. Stanczyk and C. Rampacek "Bureau of one RI 6193, 1963). Since the sulfides are very resistant, The solution according to the state of the art must always contain free sulfuric acid or pyrite be added to the leaching process if the concentrate does not contain sufficient amounts of pyrite contains. This also applies in the event that copper or Copper-nickel concentrates After a fine grinding in an agitator mill (attritor) with the addition of anion-active Substances or of alkali hydroxides, especially caustic soda at temperatures of about 110 ° C under less high pressure (interpreted OE patent applications A 98/73 and A 1516/73 (corresponding to OE-PS 319 616 and 319 617)).

In the first case, the whole is leached at temperatures above 160 ° C Material oxidizes existing sulfur to SO4 "ions, so that primarily the sulfates of Copper (cuSo4) and iron (Fe2 (S04) 5) occur as reaction products. The ferric sulfate hydrolyzes at these temperatures, in particular at 200 ° C to 95% to Fe203 and 5 to basic ferric sulphate (Fe (SO4) OH), which releases acid. The iron oxide or the basic ferric sulphate is in equilibrium with the free sulfuric acid. So there is z. B. at 2000C an equilibrium between 70 g of free sulfuric acid and 12 g ferric iron.

In the second case, the im leached at temperatures of around 110 ° C Material present sulfur to 80% in elemental sulfur and 20% in sulphate ion S04 "; so there is usually not enough S04" available for the Copper as copper sulfate and the iron as jarosite to bind Na [Fe3 (SO4) 2 (0H) 63, which is why sulfuric acid must be added before the leaching for this reason alone.

For leaching copper pebbles or other copper and sulphurous It is the starting materials from wirtr economic advantage, a concentrated one Obtain copper sulphate solution either directly or with the interposition is subjected to solvent extraction of reducing electrolysis; more concentrated than ever the copper sulphate solution is obtained, the smaller the leaching autoclave volume required.

However, the amount of dissolved copper is upwards under operating conditions given by the saturation concentration at room temperature. In the event of operational shutdowns the solubility of copper sulphate at room temperature should not be exceeded, otherwise salts will crystallize out in pipes and valves. This solubility limit is around 60 g Cu / liter.

On the other hand, for the downstream reduction electrolysis the Ferrie iron content of the solution should not be more than 4 liters, so that the current efficiency does not sink too much. If you first relate the calculations to pure copper pebbles Cu Fe S2, this results from taking into account the maximum amount of soluble copper a use of about 175 g of concentrate per liter of water, resulting in an amount of 88 g Free sulfuric acid results per liter, which in turn is about 13 g of dissolved ferrous iron is in equilibrium, so that the solution for the economic implementation of the Copper electrolysis contains too much ferrous iron.

The invention is based on the object of a method for hydrometallurgical Processing of copper gravel concentrates, copper-nickel concentrates and residues, Intermediate products and flue dusts of the pyrometallurgical smelting of non-ferrous metal ores and their scrap waste, in which the finely crushed Exhaust substances are leached with oxygen under pressure in such a way that a Solution, if possible honing a copper content of up to 60 g / l and a disene content of at most 4 g / l is obtained.

According to the invention, this object is achieved in that the starting materials in the case of pyrite-containing copper or copper ì4iczel concentrates without added acid, otherwise with the addition of acid at temperatures of 160 to 2000C to set a The copper content of the solution can be leached up to 60 g / l and the resulting amount Free sulfuric acid content is lowered to around 20 g / l by either Adds substances to the pressure leaching solution which dissolve with the consumption of sulfuric acid and even contain no or only small amounts of sulfur, or by using the Pressure leaching solution decoppered by solvent extraction, the decuppered solution for Leaching of finely ground copper or copper-nickel concentrates used at around 110 ° C, the solution obtained thereby is decuppered by solvent extraction and the two coppers containing solvent extracts combined.

It is also preferable to bring one or the other alternative the pH of the pressure leaching solution or the leaching solution of the second leaching on 1.5 to 2.

This results in addition to the desired lowering of the dissolved Ferrieisengenalts below 4 g / l prevents the formation of ferrites, which the Reduce the copper yield sensitively, and it also shows the Advantage, that then arsenic contents in the processed concentrate up to 2.1 1C, 0! with I) back digestion Solutions with only 0.07 g arsenic / liter result, while usually because of the Arsenic levels related difficulties only 0.1 'arsenic level was tolerable.

For the first alternative, i. H. for the addition of sulfuric acid Consuming substances for the pressure leach solution, preferably substances are used which themselves contain copper or other valuable, soluble sulphate-forming metals. For example, fly ash with a high zinc content is suitable for this purpose of tin and lead, ball mill dust with considerable zinc and copper contents and low tin and lead contents, cement copper with a very high copper content as well a meal from the lead smelting with considerable amounts of arsenic, nickel, and antimony and copper.

The invention is based on a few exemplary embodiments and two Flow charts corresponding to the two alternatives are explained in more detail.

A) Working method with the addition of substances that consume sulfuric acid for 160-200 ° C pressure leach solution.

A copper concentrate with 28.3% Cu, 22.9% Fe, 28.5% S, 0.56% As. The following additives were used: purely oxidic material, i. H. Flu + dust from the shaft furnace of a scrap metal smelter with 66.0% Zn, 1.5% Sn, 6.1, Pb; mixed lmaterial: a ball mill dust from processing waste, slag and Dross in a non-ferrous metal foundry with 23.01% Cu, 0.25% Sn, 29.4% Zn (of which 24.1% as ZnO), 0.7% Pb, 0.7 Fe; Cement copper with 88.7% Cu, 0.2% 5, 0.6% Fe and a meal from lead smelting with 16.5% Cu, 25.0 Ni, 2.5% Fe, 1.7% S, 32.0% As, 17.2 Sb. 6 kg of ore concentrate were added to leach the concentrate 40 liters of water and the specified amounts of additional material to 1600C heated and an oxygen pressure of i5 at created. Because the reaction is very strong is exothermic, the temperature rose to 1900C within 15 minutes and then became kept at this level by additional cooling. The water vapor pressure is at this temperature about 12 at, so that the oxygen partial pressure in! Autoclaves 9 at fraud.

A gassing mixer ensured that the gas was well dispersed in the Liquid. After about 1 hour, the reaction stopped, which was indicated by a drop the temperature in the autoclave with the heating and cooling switched off. To Cooling to 90 ° C. and letting down the pressure, the autoclave was emptied and the solution and residue separated by filters.

1. Example Use of fly ash.

1.695 kg of fly ash were added to 6 kg of copper concentrate. after the leaching was a solution with 43 g / liter Cu, 28 g / liter Zn, 2.4 g / liter Fe, 0.04 g / liter As and 20.3 g / liter H2SO4 achieved.

2nd example Use of ball mill dust To 6 kg of copper concentrate 2.104 kg of ball mill dust was added. After the leaching was a solution with 54 g / liter Cu, 15 g / liter Zn, 2.8 g / liter Fe, 0.04 g / liter As and 20.7 g / liter f12S04 scored.

3rd example Use of cement copper. 5 kg of copper concentrate were added 1.025 kg. Cement copper added. After the leaching, a solution with 58.0 g / liter Gu, 2.0 g / liter Fe, 0.04 g / liter As and 20.5 g / liter XI2S04.

4th example Use of food To 6 kg of copper concentrate were 2,) 55 kg of food added. After leaching, a solution with 52 g / liter Cu, 15 g / liter Ni§), 8 g / liter Fe, 0.2) g / liter As and 18.7 g / l H2SO4.

Of course, instead of the substances listed here other metallic, oxidic or mixed substances, e.g. B. from grinding dust the fettling shop, granulated black copper individually or mixed as an additive to Copper concentrate, the composition of which also fluctuates between 10 and 55% Cu can use the means: The resulting solution should not be more than 60 g / liter Cu and about 20 g / liter contain free sulfuric acid; the components are to be coordinated so that the acid-consuming Constituents an excess of those formed from the oxidation of the preceding sulfur Allow free acid of about 20 g / liter to remain.

The iron and arsenic contents are then very low, the former below 4g / liter.

The solution thus obtained can, because of its purity, directly Subjected to reducing electrolysis and up to a Cu content of about 5 g / liter be honored. The remaining copper must then be precipitated by cementation with iron and as such are fed back into the process. Because of the high acid content will be substantial Amounts of pilaster scrap consumed for cementation will. Therefore and because of the possibly occurring content of recoverable metals like zinc and nickel, it is recommended to remove the copper by solvent extraction, e.g. B. to extract by the specific for Cu acting "LIX" and by re-extraction with a brewable copper electrolyte, such as B. 50 g / liter Cu and 150 g / liter To separate H2SO4 for the reduction electrolysis, because in addition to the metals Zn and Ni still come from the gait, possibly Al and Mg, which may interfere with each other the electrolysis would be noticeable. During the extraction, the Cu ions exchanged for the H ions, d. H. the remaining solution freed from Cu becomes considerably acidic. This free acid can be beneficial for oxidic leaching or semi-oxidic products and thus for the extraction of the valuable contained therein Metals e.g. B. Zn can be used.

This is to be done with an example based on the products already described Copper concentrate flue dust, ball mill dust and the flow chart shown in FIG be explained, which is adjusted to a technical scale and for the throughput of 1 t concentrate.

5. Example When leaching 1 t concentrate of the above Composition and under the conditions described remain after deducting the amount of sulfuric acid for the formation of CuSO4 and Fe2 (SO4) 3 as well as for maintaining a pH value of 1.5 about 215 kg of sulfuric acid as Excess. In preliminary tests was established. that all components of the fly ash and 30% of the ball mill dust soluble in dilute sulfuric acid at room temperature ind. It therefore seemed appropriate The pressure leaching can only be used for substances that are under normal conditions are not soluble in sulfuric acid. This is why it is called an acid-consuming surcharge for pressure leaching only the part of the ball mill dust which is insoluble at room temperature used. After pressure leaching, insoluble gangue, iron oxide, become basic Ferric sulfate, PbSO4 and SnO2 filtered off and the remaining solution by solvent extraction freed from copper. This now relatively strongly acidic solution is used to To leach flue dust and ball mill dust under normal conditions, whereby it is advisable neutralized to a pH of 5.5 to 5. You can get the Repeat zinc sulfate solution, d. H. instead of water for the pressure digestion of Use sulphidic copper ores until the solution contains about 100 g / l zinc.

After partial neutralization with fly ash, Xugelmühlenstaub or other oxidic zinc precursors, the solution is made with lime or milk of lime added to precipitate all zinc as Zn (OH) 2 and all SO42- as gypsum.

The precipitate is separated from the residual solution via thickener and Treated with cell acid of zinc electrolysis, with the filled zinc again goes into solution and can now be tinned in a subsequent electrolysis karl.

Instead of copper concentrates, copper-nickel concentrates can also be used be used. An example should explain this.

6. Example A concentrate with the following composition was available: 6.48% Cu, 7.98% Ni, 39.75% Fe, 30.1% S, 15.7% gangue (of which 12.48% are soluble). 6 kg concentrate were mixed with 2.03 kg of cement copper of the composition given above at 1900C the conditions also outlined above. It became a solution with 54 g / l Cu, 12 g / l Ni, 2.1 g / l Fe and 21.0 / 1 H2S04 obtained. Here is recommended in all cases a solvent extraction for both copper and nickel. Both extraction methods as well as the subsequent reduction electrolyses correspond to the state of the art. In addition to the copper-nickel concentrate used as an example, you can also use high arsenic Copper or nickel concentrates, which have so far hardly been used, are used, because the iron in front and the condition pH = 1.5 - 2 are sufficient to during the pressure digestion to remove the arsenic completely.

B) Operation with 160-200 ° C pressure leaching and subsequent leaching at around 1100C.

7. Example 1 t of copper concentrate with 28.3% was available Cu, 22.9 Fe, 28.5% 5, 0.56 As, 19.4% gait. The following should be noted as operating data: 150 liters of solid matter, lye temperature 1900C, oxygen partial pressure 5 atmospheres, lye # duration 1h or long temperature 110 ° C, oxygen partial pressure 1 atm, leaching time 30 minutes. 5% of the leading iron from the leaching at 190 ° C was found to be Fe (S04) (OH) and 95 formed as Fe2O3; this resulted in an excess of sulfuric acid of 828.15 kg, of which 4D5.97 kg are required for the formation of copper sulphate will and) 92.18 kg partly as free sulfuric acid, partly as ferric sulfate in the solution remain. The solution thus formed contained a Ni value of about 1 also 12 g / liter ferric ions and 42 liters Cu. This solution was known after Methods and chemicals decoppered by solvent extraction. In doing so, the copper replaced by hydrogen ions and more free sulfuric acid in an 'amount of 4) 5.97 kg formed, so that after the solvent extraction a total of 828.15 kg free Sulfuric acid were present in the residual liquor.

When leaching the concentrate after appropriate pretreatment at 1100C 80% of the leading sulfur was set free and elementary 20% oxidized to SO4 "ions. In this case, the iron was excreted as Na-Jarosite NaFe3 (SO4) 2 (OH) 6.

When using 1 t of concentrate, 54.66 kg of NaOH were required for the precipitation required, which are expediently added during the grinding in the attritor, and 268,11 kg H2S04.

Another 435.97 kg of sulfuric acid were used to form copper sulfate 20 g / liter or 133.34 kg were used to maintain a pH value of 1.5 needed. A total of 837.42 kg of sulfuric acid were used to leach 1 t of concentrate needed, but only produced 174.55 kg during the leaching process, so that in itself a deficit of 665.07 kg of sulfuric acid was formed. This deficit was caused by the leaching process According to the invention, excess sulfuric acid formed at 1900C is covered. The at the leaching of 1 t concentrate at 190 ° C and the subsequent solvent extraction In the present case, the resulting acid was sufficient for about 1.25 t of concentrate to leach at low temperature and low pressure.

The flow chart shown in FIG. 2 is shown in diagrammatic form in the upper and middle part of the process.

The streams from the solvent extraction of the leachate from 1900C and from 1100C are finally combined and together in a reducing electrolysis processed into copper.

3rd example A copper-nickel concentrate with 6.48% was available Cu, 7.98% Ni, 39.75% Fe, 30.1% S, 15.7% gangue (of which 12.48 insoluble). The operating data and conversion data were the same as in Example 7, only that Ni was also used as nickel sulfate went into solution. Since the metal content of the concentrate is much lower than that of pure copper concentrate, we recommend increasing the solids content of 150 g / liter in example 7 to 300 g / liter in this example. 1 t concentrate after leaching an excess of sulfuric acid of 4) 6.45 kg, which is after the Solvent extraction of copper increased to 5) 6, o5 kg. During the leaching at 1100C it was formed a deficit of 707.5 kg for 1 t concentrate use. Accordingly, with the excess acid the leaching of 1 t of concentrate at 190 ° C, 757 kg of concentrate can be leached at 110 ° C. The full flow chart of Fig. 2 shows the course of the process, which differs from the example 7 differs through the additional solvent extraction for nickel.

In both cases, the need for additional chemicals is low and is limited to caustic soda, which is used both for fine grinding and is also required for the precipitation of jarosite, and for lime setting the pH value required for the extraction of nickel or for neutralization of the return water.

Since the solution has a pH of 1.5 after the second leaching, The use of concentrates containing arsenic is also possible here. Even if the first one Leaching larger amounts of arsenic remain in solution because of the low pH value, they are separated from the copper by the solvent extraction and remain harmless. In the second leaching, however, they are reduced to a few except for very small quantities hundredth of a gram precipitated.

Claims (5)

Claims 1. Process for hydrometallurgical processing of copper pyrites concentrates. Copper-nickel concentrates and residues, intermediate products and flue dust of the pyrometallurgical smelting of non-ferrous metal ores and their scrap waste, in which the finely ground raw materials are leached with oxygen under pressure It is clear that the starting materials contain pyrite in the case of / copper or copper-nickel concentrates without added acid, otherwise with acid addition at temperatures from 160 to 2000C to adjust a copper content of the solution up to 60g / l can be leached and the s-ich thereby adjusting content of Free sulfuric acid is lowered to about 20 g / 1 by either the pressure leach solution Adding substances that dissolve under the consumption of sulfuric acid and no or themselves contain only small amounts of sulfur, or by using the pressure leach solution Decuppered by solvent extraction, the decuppered solution for leaching finely ground Copper or copper-nickel concentrates o used at about 110 G, the resulting Solution decoppered by solvent extraction and the two copper-containing solvent extracts united. 2 Method according to claim 1 with additive to the pressure leaching solution, characterized in that the substances to be added are those which themselves Contain copper or other valuable, soluble sulphate-forming metals 3. Procedure according to claim 2, characterized in that the substances to be added are flue dust with high zinc content and contents of tin and lead, ball mill dust with considerable zinc and copper contents and low tin and lead contents, cement copper with a very high copper content and / or a meal from lead smelting with considerable Used in arsenic, nickel, antimony and copper content. 4. The method according to Anspruen) with additive to the pressure leach solution, characterized in that the pH value resulting from the pressure leaching adjusts the solution to 1.5 to 2. 5. The method according to claim 1 with additional leaching at about 1100C, characterized in that the resulting in the additional leaching Adjusts the pH of the solution to 1.5 to 2.