A process for directly recovering tellurium and copper from tellurium-containing waste residues

Abstract

The present invention relates to a process for directly recovering tellurium and copper from tellurium-containing waste residues. The process involves reacting a sulfuric acid solution, sodium nitrate with the tellurium-containing waste residues, so that copper and silver in the tellurium-containing waste residues enter the solution, while metals such as tellurium, lead, bismuth, and gold remain in the leaching residues, separating copper from tellurium, replacing copper in the leaching solution with iron powder to obtain sponge copper, then leaching tellurium in the leaching residues with a hydrochloric acid solution, and obtaining crude tellurium powder after reduction with sulfur dioxide. The direct recovery rates of lead, tellurium, silver, and copper are all greater than 98%. The direct recovery rate of valuable metals in the whole process is high, and the production cost is relatively low.

Description

Technical Field

[0001] The invention relates to a process for directly recovering tellurium and copper from tellurium-containing waste slag, belonging to the technical field of comprehensive recovery of precious metals. Background Art

[0002] During the smelting process of lead, bismuth and copper, tellurium will be enriched in tellurium-containing waste slag, and copper and tellurium need to be recovered. In addition, tellurium-containing semiconductor materials, electronic solders, integrated circuit leads and other waste materials also need to comprehensively recover the valuable metals therein. These tellurium-containing materials mainly contain tellurium, copper, silver, lead, gold, bismuth and other valuable metals. At present, the main method for recovering these valuable metals is to use acid leaching to leach copper and tellurium therein, and then separate and recover copper and tellurium in the leachate. This method requires that all copper and tellurium be leached out and copper and tellurium must be separated from the leachate. However, copper telluride is easily formed when copper and tellurium are separated, which makes the separation of copper and tellurium incomplete, thereby causing the loss of copper or tellurium.

[0003] On April 26, 2024, China Invention Patent Application Publication No. CN117926009A disclosed a method for high-value utilization of silver-rich gold slag, which comprises mixing the silver-rich gold slag with concentrated sulfuric acid to obtain a slurry; the silver-rich gold slag contains selenium, tellurium, silver, gold and copper elements; the slurry is subjected to oxidative roasting under the condition of introducing a carrier gas, and the selenium in the silver-rich gold slag is oxidized into selenium dioxide gas, and the tellurium is oxidized into tellurium dioxide slag, respectively. to roasting slag and flue gas containing selenium dioxide; absorb the flue gas containing selenium dioxide and recover selenium from the obtained absorbent; remove copper from the roasting slag by water leaching to obtain copper-removing slag; alkali-leach the copper-removing slag with NaOH solution to convert tellurium dioxide in the copper-removing slag into sodium tellurite, separate the solid and liquid, and obtain alkaline leaching solution containing sodium tellurite and leaching slag respectively; recover gold and silver from the leaching slag; neutralize the alkaline leaching solution containing sodium tellurite and recover tellurium. The whole process uses both pyrometallurgy and hydrometallurgy, uses both sulfuric acid and sodium hydroxide, has a long process flow and high production cost, and the silver is still in the leaching slag, and the silver is not directly recovered.

[0004] On October 21, 2022, China's invention patent application publication number CN115215303A disclosed a method for extracting tellurium dioxide from tellurium copper slag, which method is to acid-leach, oxidize and filter the wet tellurium copper slag in sequence to obtain acid-leach oxidation filter washing residue and acid-leach oxidation filter washing liquid, and then alkali-leach and filter the acid-leach oxidation filter washing residue to obtain alkali-leach filter washing residue and alkali-leach filter washing liquid, and then wet-purify and dry the alkali-leach filter washing liquid to obtain tellurium dioxide solid; this method first oxidizes the tellurium by acid leaching and then alkali-leaches it, and also uses both sulfuric acid and sodium hydroxide, with a long process flow and high production cost, and no direct recovery of silver and copper.

[0005] On August 23, 2022, China Invention Patent Application Publication No. CN114933285A disclosed a method for selectively recovering tellurium from copper anode mud. The method provides a method for selectively recovering tellurium from copper anode mud. Specifically, it is a method for selectively leaching selenium and tellurium from copper anode mud, and reducing tellurium to metallic tellurium, effectively enriching valuable metals such as copper, silver, and gold. The present invention adopts oxygen pressure alkaline leaching-Na 2 S leaching—SO 2 Reduction process. In the oxygen pressure alkali leaching process of the present invention, more than 99% of tellurium is enriched in the slag, and Na 2 The tellurium leaching rate in the S leaching process can reach 94%, SO 2 The tellurium recovery rate in the reduction process can reach more than 95%. This method uses oxygen pressure alkaline leaching and sodium sulfide leaching, silver is not leached and some copper will be lost, the cost is relatively high, the tellurium recovery rate is relatively low, and it only enriches copper and silver without separating them.

[0006] The above prior art, whether using an alkaline system for leaching, using hydrochloric acid plus sodium nitrate for leaching, or using pure sulfuric acid for leaching, cannot leach silver, and at the same time, some copper will also be lost; if pure nitric acid is used, silver can be leached, but the amount of nitric acid used is large and more waste gas is generated. Summary of the invention

[0007] In view of the above-mentioned problems existing in the prior art, the present invention proposes a process for recovering copper and tellurium from tellurium-containing waste slag, which can directly separate copper and tellurium from solid and liquid without separating copper and tellurium from the solution, thereby improving the direct recovery rate of copper and tellurium and lowering the production cost of the entire process.

[0008] The technical solution of the present invention to solve the above problems is:

[0009] A process for recovering copper and tellurium from tellurium-containing waste residues is to use a leaching method of sulfuric acid and sodium nitrate at a temperature of 85°C-95°C to allow copper and silver to enter the solution, while valuable metals such as tellurium, lead, and gold do not enter the solution, thereby separating copper and silver from tellurium and lead; for the copper and silver in the solution, the silver and copper in the solution are recovered by using a method of sodium chloride precipitation of silver and iron powder replacement of copper; the tellurium in the leached residue is leached by a hydrochloric acid solution method, and sulfur dioxide is used for reduction to obtain crude tellurium powder; the main chemical reactions are as follows:

[0010] 2H 2 SO 4 +2NaNO 3 +Cu=CuSO 4 +Na 2 SO 4 +2H 2 O+2NO 2

[0011] 2H 2 SO4 +2NaNO 3 +2Ag=Ag 2 SO 4 +Na 2 SO 4 +2H 2 O+2NO 2

[0012] 9H 2 SO 4 +18NaNO 3 +4Te=2Te 2 O 3 (OH)NO 3 +9Na 2 SO 4 +8H 2 O+16NO 2

[0013] The specific steps are as follows:

[0014] (1) Primary leaching: Weigh a certain amount of tellurium-containing waste slag, control the amount of sulfuric acid added to 50-70% of the mass of the tellurium-containing waste slag, the amount of sodium nitrate added to 60-80% of the mass of the tellurium-containing waste slag, the liquid-to-solid volume mass ratio to 3-4:1, react at 85℃-95℃ for 150min-180min, and filter to obtain crystalline Te 2 O 3 (OH)NO 3 The primary leaching residue and copper-silver solution;

[0015] (2) Silver precipitation: at room temperature, add sodium chloride in an amount of 100% to 120% of the mass of silver in the copper-silver solution to the copper-silver solution, react for half an hour, and then filter to obtain silver chloride and a copper-containing solution;

[0016] (3) Copper replacement: add iron powder with a mass of 120%-150% of the copper in the copper solution to the copper-containing solution, react at room temperature for 1 hour, and then filter to obtain sponge copper and copper replacement liquid. The copper replacement liquid is sent to the wastewater treatment workshop for treatment;

[0017] (4) Secondary leaching: for crystalline Te 2 O 3 (OH)NO 3 The first leaching residue is weighed, the amount of hydrochloric acid added is controlled to be 60-70% of the mass of the first leaching residue, the liquid-solid volume mass ratio is 3-5:1, the reaction time is 120min~150min at 85℃-95℃, and after the reaction is completed, the second leaching residue and the tellurium-containing solution are obtained by filtration. The second leaching residue is the lead-gold valuable metal enriched residue, which can be directly sent to the lead recovery system;

[0018] (5) Tellurium recovery: Sulfur dioxide is introduced into the tellurium-containing solution to obtain crude tellurium powder.

[0019] Compared with the prior art, the present invention has the following technical effects:

[0020] (1) In the primary leaching process, sulfuric acid and sodium nitrate are used as leaching agents, and the amount of sulfuric acid and sodium nitrate is strictly controlled to ensure that tellurium is not leached, while copper and silver are leached, and metals such as lead and bismuth are left in the leaching residue. This makes the copper-silver solution relatively pure, which is conducive to the separation of copper and silver;

[0021] (2) The present invention uses sodium chloride to precipitate silver and iron powder to replace copper to recover the silver and copper in the solution; uses hydrochloric acid solution leaching to leach tellurium from the leached residue, and uses sulfur dioxide to reduce it to obtain crude tellurium powder; this can not only improve the direct recovery rate of tellurium and copper, but also directly recover silver from the tellurium-containing material, thus achieving two goals at one stroke. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Attached Figure 1 It is a process flow chart of the present invention.

[0023] In the figure, tellurium-containing waste residue is leached once with sulfuric acid and sodium nitrate, and filtered to obtain primary leaching residue and copper-silver solution; sodium chloride is used to precipitate silver in the copper-silver solution, and the copper-containing solution and silver chloride are filtered; iron powder is used to replace copper in the copper-containing solution to produce sponge copper and copper-replaced liquid, and the copper-replaced liquid is sent to the wastewater treatment workshop for treatment;

[0024] The primary leaching residue is subjected to secondary leaching with hydrochloric acid; after the reaction is completed, the secondary leaching residue and the tellurium-containing solution are obtained by filtration; the secondary leaching residue is the lead-gold valuable metal enriched slag, which can be directly sent to the lead recovery system for conventional process treatment; sulfur dioxide is introduced into the tellurium-containing solution to obtain crude tellurium powder. DETAILED DESCRIPTION Example 1

[0025] (1) Primary leaching: weigh 100 g of tellurium-containing waste slag produced by crude lead refining, which contains 31.26% tellurium, 25.32% copper, 0.83% silver, 10.28% lead, and 23.28 g / t gold, add 40 mL of sulfuric acid, 70 g of sodium nitrate, and 300 mL of water, react at 90 ° C for 160 min, and filter after the reaction to obtain 80.28 g of primary leaching slag and 305 mL of copper-silver solution (2.69 g / L silver, 82.18 g / L copper);

[0026] (2) Silver precipitation: at room temperature, add 0.86g sodium chloride to the copper-silver solution, react for half an hour and filter to obtain 1.10g silver chloride and 303mL copper-containing solution, which contains 74.50% silver and has a silver direct recovery rate of 98.73%; (3) Copper replacement: add 32g iron powder to the copper-containing solution, react for 1 hour at room temperature and filter to obtain 30.14g sponge copper and copper replacement solution, which contains 82.33% copper and has a copper direct recovery rate of 98.00%. The copper replacement solution is sent to the wastewater treatment workshop;

[0027] (4) Secondary leaching: Add 50 mL of hydrochloric acid and 300 mL of water to the primary leaching residue, react at 90 °C for 130 min, and filter to obtain 38.23 g of secondary leaching residue and 345 mL of tellurium-containing solution, which contains 89.70 g / L of tellurium. The secondary leaching residue is enriched slag containing valuable metals such as lead and gold, with a lead and gold recovery rate of more than 99%. The enriched slag can be directly sent to the lead recovery system;

[0028] (5) Tellurium recovery: Sulfur dioxide was introduced into the secondary leaching solution until the tellurium concentration in the solution was less than 0.1 g / L. The solution was then filtered to obtain 33.99 g of crude tellurium powder, containing 90.32% tellurium and a tellurium direct recovery rate of 98.20%. Example 2

[0029] (1) Primary leaching: weigh 1000 g of tellurium-containing waste residue, which contains 22.32% tellurium, 30.13% copper, 0.52% silver, 7.23% lead, and 18.28 g / t gold, add 299 mL sulfuric acid, 750 g sodium nitrate, and 3000 mL water, react at 85 ° C for 170 min, and filter after the reaction to obtain 750.23 g of primary leaching residue and 3250 mL of copper-silver solution (1.58 g / L silver, 92.24 g / L copper);

[0030] (2) Silver precipitation: At room temperature, add 5.656 g of sodium chloride to the copper-silver solution. After reacting for half an hour, filter and obtain 6.91 g of silver chloride and 3150 mL of copper-containing solution, of which the silver content is 74.23% and the direct silver recovery rate is 98.64%.

[0031] (3) Copper replacement: 390 g of iron powder was added to the copper-containing solution, and the mixture was reacted at room temperature for 1 hour and then filtered to obtain 358.02 g of sponge copper and a copper replacement solution, which contained 83.28% copper and had a direct copper recovery rate of 98.95%. The copper replacement solution was sent to the wastewater treatment workshop;

[0032] (4) Secondary leaching: Add 488 mL of hydrochloric acid and 2500 mL of water to the primary leaching residue, react at 90 °C for 130 min, and filter to obtain 363.28 g of secondary leaching residue and 2896 mL of tellurium-containing solution, which contains 76.30 g / L of tellurium. The secondary leaching residue is enriched slag containing valuable metals such as lead and gold, with a lead and gold recovery rate of more than 99%. The enriched slag can be directly sent to the lead recovery system;

[0033] (5) Tellurium recovery: Sulfur dioxide was introduced into the secondary leaching solution until the tellurium concentration in the solution was less than 0.1 g / L. The solution was then filtered to obtain 244.22 g of crude tellurium powder, containing 90.11% tellurium and a tellurium direct recovery rate of 98.59%.

[0034] The key technologies of the present invention are:

[0035] (1) In a single leaching process, more than 98% of the copper enters the solution, and more than 98% of the tellurium remains in the leaching residue. In this way, the copper enters the leaching solution, while the tellurium remains in the leaching residue, and the copper and tellurium are directly separated from the solid and liquid, without the need to separate the copper and tellurium from the solution, thereby improving the direct recovery rate of copper and tellurium;

[0036] (2) While leaching copper, more than 99% of the silver enters the solution, and the silver in the tellurium-containing waste slag is directly recovered;

[0037] (3) In the primary leaching process, sulfuric acid and sodium nitrate are used as leaching agents, and the amount of sulfuric acid and sodium nitrate is strictly controlled to ensure that tellurium is not leached, while copper and silver are leached, and metals such as lead and bismuth are left in the leaching residue. This makes the copper-silver solution relatively pure, which is conducive to the separation of copper and silver;

[0038] (4) Since most of the copper has been leached out and most of the tellurium has been oxidized during the first leaching process, only hydrochloric acid needs to be added in the second leaching, and no oxidant needs to be added. Since most of the copper has been leached out in the first leaching, the tellurium-containing solution obtained by the second leaching is relatively pure, with the copper content being less than 0.5 g / L. More than 90% of crude tellurium powder can be obtained by reduction. In the whole process, the direct recovery rate of copper, tellurium and silver is more than 98%, and the purity of the products obtained is relatively high.

Claims

1. A process for recovering copper and tellurium from tellurium-containing waste slag, characterized in that At a temperature of 85°C-95°C, a leaching method of sulfuric acid plus sodium nitrate is used to make copper and silver enter the solution, while tellurium, lead and gold do not enter the solution, so as to separate copper and silver from tellurium and lead; for the copper and silver in the solution, the silver and copper in the solution are recovered by using sodium chloride to precipitate silver and iron powder to replace copper; the tellurium in the leached residue is leached by hydrochloric acid solution, and sulfur dioxide is used for reduction to obtain crude tellurium powder; the specific steps are as follows: (1) Primary leaching: Weigh a certain amount of tellurium-containing waste slag, control the amount of sulfuric acid added to be 50-70% of the mass of the tellurium-containing waste slag, the amount of sodium nitrate added to be 60-80% of the mass of the tellurium-containing waste slag, the liquid-solid volume mass ratio to be 3-4:1, react at 85°C-95°C for 150min-180min, and filter after the reaction to obtain a primary leaching slag containing crystalline Te2O3(OH)NO3 and a copper-silver-containing solution; (2) Silver precipitation: at room temperature, add sodium chloride in an amount of 100% to 120% of the mass of silver in the copper-silver solution to the copper-silver solution, react for half an hour, and then filter to obtain silver chloride and a copper-containing solution; (3) Copper replacement: add iron powder with a mass of 120%-150% of the copper in the copper solution to the copper-containing solution, react at room temperature for 1 hour, and then filter to obtain sponge copper and copper replacement liquid. The copper replacement liquid is sent to the wastewater treatment workshop for treatment; (4) Secondary leaching: Weigh the primary leaching residue containing crystalline Te2O3(OH)NO3, control the amount of hydrochloric acid added to 60-70% of the mass of the primary leaching residue, and the liquid-solid volume mass ratio to 3-5:

1. The reaction time is 120 min to 150 min at 85°C to 95°C. After the reaction is completed, filter to obtain secondary leaching residue and tellurium-containing solution. The secondary leaching residue is the lead-gold valuable metal enriched residue, which can be directly sent to the lead recovery system; (5) Tellurium recovery: Sulfur dioxide is introduced into the tellurium-containing solution to obtain crude tellurium powder.

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