MXPA05005997A

MXPA05005997A - Method for treating slag.

Info

Publication number: MXPA05005997A
Application number: MXPA05005997A
Authority: MX
Inventors: Saarinen Risto
Original assignee: Outokumpu Oy
Priority date: 2002-12-05
Filing date: 2003-11-24
Publication date: 2005-08-18
Also published as: PE20040630A1; US20060037435A1; AU2003283455A1; FI20022150A0; JP2006509103A; AR042301A1; EP1579017A1; CN1720342A; FI20022150A; KR20050085402A; EA200500756A1; BR0317061A; WO2004050925A1; FI115638B; PL376932A1

Abstract

The invention relates to a method for treating slag created in the production of blister copper processed directly from concentrate in a suspension smelting furnace, such as a flash smelting furnace, in order to recover the copper, so that at least part of the slag is leached in at least one step.

Description

METHOD FOR SCREEN TREATMENT Field of the Invention The invention relates to a method that is defined in the preamble of claim 1 for the treatment of slag created in the production of vesicular copper.

Background of the Invention The production of vesicular copper from sulfur concentrates directly in a single stage in a suspension reactor, such as an ultra-fast melting furnace, is economically sensitive, with certain boundary conditions. Among the most notable problems that exist in the direct production of vesicular copper is the scorification of copper and the large amounts of slag that are created. In order to ensure a sufficient recovery of the copper, the amount of copper found in the slag must be recovered in relation to the slag cleaning. Apart from the amount of slag, another problem involves the large amounts of heat created in the combustion of sulfur concentrates. In that case, a low oxygen enrichment in the process air is applied, which means that the heating of the nitrogen contained in the process air balances the heat economy. However, this produces a large amount of process gases, which again results in a large furnace space and above all in large gas processing units. In the case where the copper content of the concentrate is sufficiently high, typically at least 37% Cu, vesicular copper production is economically possible directly in one stage. The thermal value of the concentrate is generally lower, the higher the copper content of the concentrate. With a high copper content, the iron sulfide mineral part is low. When the concentrate described above is processed, a sufficiently high oxygen enrichment can be used and, as a result, the gas quantities can be maintained at a moderate level. Also a concentrate with a low copper content is adequate in the production of vesicular copper, if it has a low iron content, in which case the amount of slag created is not noticeably large. From the Finnish patent application No. 982818 a method for the production of vesicular copper is known, in which method, in addition to the concentrate, molten and cooled copper matte are conducted to a casting reactor. Now a smaller amount of slag has been created in proportion to the amount of vesicular copper produced than with the traditional method. Now copper losses in slag have also been reduced. The slag created is further processed either in a single stage cleaning process or preferably in a two stage cleaning process. A two-stage slag cleaning method includes either two electric furnaces or an electric furnace and a slag concentrate plant. In the electric furnace the slag is reduced by coke, so that the precious metals bound in the slag phase are reduced and separated as a distinctive copper phase below the slag layer. In the event that the slags are processed in a slag concentration plant, the slag concentrate can be fed back to the smelting reactor. The vesicular copper is driven to be refined in an anode furnace. If the slag is processed in a single stage in an electric furnace, so that the amount of copper in the slag is economically insignificant, the iron content in the vesicle is still so high that a separate treatment for the vesicular is often required in a converter. One method is the pre-treatment of electric furnace, where vesicular copper created is processed together with bulk vesicular in an anode furnace, but there is still a lot of copper in the slag that for economic reasons must be recovered by technical means of concentration.

OBJECTIVES OF THE INVENTION The objective of the invention is to introduce a new method for the treatment of slag created in the production of vesicular copper that is produced directly from a concentrate. A particular objective of the invention is to achieve a more effective and more advantageous way, with respect to the global economy, to recover copper slagging in the production of vesicular copper.

The invention is characterized by what is established in the characterizing part of claim 1. Other embodiments of the invention are characterized by what is established in the rest of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is described in more detail below and with reference to the accompanying drawings, in which Figure 1 is a diagram of a process according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The method according to the invention has many advantages. According to the method, the copper contained in the slag created in the production of vesicular copper produced directly from the concentrate is advantageously recovered. The method of the invention simplifies the recovery of the copper and, in addition, the method makes possible an improved control of the impurities. The recovery of the copper contained in hydrometallurgical slag reduces the energy consumption compared to the reduction of the electric furnace. In addition, gas and dust emissions are reduced compared to pyrometallurgical recovery. Figure 1 illustrates a method according to the invention for slag processing, that is, vesicle slag, created in the production of vesicular copper that is produced in a suspension smelting furnace, such as an ultra-fast smelting furnace, with in order to recover the copper, in which case at least a part of the slag is leached in at least one stage. The concentrate of copper, flux and air enriched with oxygen are fed to the smelter 1 in a smelting furnace in suspension, such as an ultra-fast casting furnace. The dry concentrate particles react rapidly in a hot suspension with air enriched with oxygen. The energy that is released in the reactions is used in the process. Part of the sulfur is oxidized in sulfur dioxide, and the iron is oxidized in iron oxides, thus creating slag with the flux. The reaction products are sedimented in the lower part of the smelting furnace in suspension, creating two separate and molten phases: vesicular copper and vesicular slag. The gases created in the process are conducted additionally, to be processed in a way that is known. The vesicular copper created in the smelting furnace in suspension is conducted to an anode oven treatment 2, where it is refined in a manner that is already known and is emptied into copper anodes. The vesicle slag created in the smelter 1 is poured out of the smelting furnace in suspension through provided circulation channels, such as tundishes, and is further conducted to be treated in order to recover the copper contained in the smelter. vesicular slag. First the vesicle slag is transferred to a granulation and grinding stage 3. The granulated vesicular slag is milled for example in a wet milling operation at a given grain size in order to obtain a larger reaction surface. In the leaching step 4, the metals contained in the vesicle slag are leached. According to the example given below, the leaching 4 is carried out under oxidation conditions with sulfuric acid, so that copper sulfate is created. The amount of sulfuric acid added is advantageously 500-900 grams per kilogram of slag. The leaching can also be carried out by means of an ammonia solution, a doric solution or as a leaching of bacteria. After the leaching stage, from the solution containing metal sulphates, the copper is separated in the copper precipitation stage 5. In the copper precipitation stage, from the solution containing metal sulphates, the copper is precipitated for example by hydroxide precipitation or sulfur precipitation. In precipitation of hydroxide, the copper is precipitated by limestone and the precipitate created and containing the copper is conducted back to the stage of smelting 1. In the precipitation of sulfur copper is precipitated by hydrogen sulfide and the precipitate created and which contains copper is conducted back to casting stage 1. Copper can also be recovered by liquid-liquid extraction and electrolysis as cathode copper.

Example In order to verify the method, sulfuric acid solution experiments were carried out in a two-liter acid-proof reactor with a lid. The reactor was provided with four flow deflector plates, a reflux condenser and an agitator. A continuous pH meter, a temperature regulator and oxygen bubbling under the agitator blades had also been connected to the reactor. A heat plate was used for heating. At the beginning of the experiment, the slag (200 grams) was leached in water, the amount of water being a little less than one liter. In all the experiments the total volume of water and sulfuric acid added was exactly one liter. The temperature of the solution was 90 ° C. The amount of sulfuric acid (H2SO4) that was added in the experiment was 806 g / 1000 g of slag. The leaching period in all the experiments was 6 hours, and mechanical agitation experiments (approximately 770 revolutions / minute) as well as oxygen (0.50 liters per minute) were applied to the experiments. Strong sulfuric acid (95% by weight content) was added gradually and at the same time the temperature was adjusted to 90 ° C. The reaction time measurement was started when all the acid had been delivered. Slurry samples were taken when 0, 2, 4 and 6 hours had passed since the beginning of the experiment. In the filtrate and precipitate of the sample, the content of copper (Cu) and iron (Fe) was analyzed. Originally the leached slag contained 32.5% Cu and 23% Fe. The analyzes and yields of the leaching obtained on the bases already provided are presented in the following table: The weight of the final precipitate was 77.4 grams and the copper content was 3.1%, which means that the total copper produced in the solution was 96.3%. The experiment was repeated under similar conditions for the slag that was, instead of cooled slowly, granulated by water directly from the molten state, so that the product obtained was finely divided with the corresponding composition. The total leaching yield obtained for copper under similar conditions was 95.8%, which is of the same order as with slow cooling slag, when the accuracy of the analysis is taken into account. From the solution, the copper was precipitated selectively by adjusting the acidity, so that the iron was precipitated in the first stage and the copper in the second stage, and in this way the unwanted iron could be separated from the copper. It is obvious to a person skilled in the art that the various preferred embodiments of the invention are not restricted to the foregoing examples only, but may vary within the scope of the appended claims.

Claims

Claims 1. A method for the recovery of copper from slag created in the production of vesicular copper processed directly from concentrate in a smelting furnace in suspension, such as an ultra-fast smelting furnace, characterized in that at least part of the slag it is leached in at least one stage to dissolve copper from the slag, the dissolved copper is precipitated and the precipitated copper is returned to the smelting process.
2. A method according to claim 1, characterized in that the slag is granulated and ground prior to leaching.
3. A method according to claim 1 or 2, characterized in that the leaching is carried out with sulfuric acid.
4. A method according to claim 1 or 2, characterized in that the leaching is carried out with an ammoniacal solution.
5. A method according to claim 1 or 2, characterized in that the leaching is carried out with a doric solution.
6. A method according to claim 1 or 2, characterized in that the leaching is carried out as a solution of bacteria.
A method according to any of the preceding claims, characterized in that after leaching, the copper is recovered by hydroxide precipitation.
8. A method according to claim 1-6, characterized in that after leaching, the copper is recovered by sulfide precipitation.
9. A method according to claim 1-6, characterized in that after leaching, the copper is recovered in a liquid-liquid extraction and electrolysis as cathode copper. A method according to claim 7 or 8, characterized in that the copper-containing slag created in the precipitation is conducted back into the smelting furnace in suspension.