Self-heating tempering and valuable metal partition recycling method for copper smelting slag

Abstract

The invention provides a self-heating tempering and valuable metal partition recycling method for copper smelting slag. The method comprises the steps that S1, a slag tempering agent is prepared from industrial sulfate waste and a low-cost carbonaceous reducing agent; s2, in the copper smelting matte smelting deslagging process, a tempering agent is added into molten slag, and phase adjustment reaction is completed through latent heat of the molten slag; s3, after the slag is slowly cooled, classifying the upper part and the lower part of materials in the slag ladle, and performing conventional crushing, ore grinding and flotation on the upper part to recover valuable metals; and S4, the lower part of sulfonium-rich slag enters a direct return smelting system or is crushed and levigated, and then copper concentrate is recycled through magnetic separation-reverse flotation. According to the copper smelting slag self-heating tempering and valuable metal partition recycling method, synergistic low-carbon treatment is conducted on copper smelting slag and sulfate waste residues according to the concept of treating waste with waste, the method has the advantages of being high in metal recycling rate, low in cost, environmentally friendly, simple in process and material and the like, good economic benefits and environmental benefits are achieved, and the industrial popularization difficulty is small.

Description

Technical Field

[0001] The invention belongs to the technical field of resource utilization of industrial solid waste in metallurgical engineering and chemical engineering, and relates to a method for self-heating tempering of copper smelting slag and zoning recovery of valuable metals. Background Art

[0002] Copper smelting slag is one of the major industrial solid wastes. According to statistics, about 2.2 to 3 tons of smelting slag are generated for every ton of mineral copper produced, and the world produces 40 to 50 million tons of copper smelting slag each year. As the quality of mineral resources continues to decline, the yield and output of copper smelting slag will further increase. Copper smelting slag is mainly composed of elements such as Cu, Fe, Si, Ca, Al, Mg, Pb, Zn, S, As, and O. Depending on the composition of the concentrate, it may also contain a small amount of Ni, Co, Au, Ag and platinum group metal elements. my country's copper smelting scale accounts for more than 43% of the world, but its dependence on raw material imports exceeds 85%. With the commissioning of new and renovated copper smelting projects, the contradiction between my country's copper smelting capacity and raw material supply will be further intensified. According to the "Geological Exploration Specifications for Copper, Lead, Zinc, Silver, Nickel and Molybdenum Minerals" (DZ / T0214-2002), the cut-off grade of copper mines in my country is 0.2wt.%, and the grade of copper ores explored and mined in recent years is around 0.3wt.%. The Cu content in the smelting slag of various copper smelters in my country is about 0.54-5.83wt.%, which is much higher than the cut-off grade of copper mines. It also contains valuable metals such as Au, Ag, Ni and Co, and has great recovery value.

[0003] At present, the industry mainly uses two methods, pyrometallurgical depletion and slag beneficiation, to recover copper from copper smelting slag. Some studies have also tried to treat it through wet processes, but wet extraction consumes a lot of reagents, the equipment is easily corroded, and the leachate and leaching slag produced during the leaching process are prone to secondary pollution, so it is less used in industry. Chile's Peport smelter uses two systems, electric furnace depletion and slow cooling-ball milling-flotation, to treat the same smelting slag. The minimum copper content of the electric furnace tailings is 0.47wt.%, and the minimum copper content of the beneficiation tailings is 0.26wt.%. Slag beneficiation is a slag treatment process commonly used by copper smelting enterprises in my country. The copper content of beneficiation tailings can be as low as 0.23wt.%. According to my country's copper smelting scale of tens of millions of tons, it is estimated that more than 50,000 tons of metallic copper are lost through beneficiation tailings each year, with a value of more than 3 billion yuan.

[0004] In response to the problem of high copper content in copper flotation tailings, there are many studies on strengthening the slag beneficiation process from the perspectives of slag conditioning and phase transformation to obtain higher flotation efficiency and lower slag copper content. Chinese patent document CN118813969A (a method for recovering valuable metals in copper slag and its application) uses sodium sulfate and a carbonaceous reducing agent to prepare a composite depleting agent, and then adds the composite depleting agent to the hot copper slag to realize the sulfidation conversion of metal oxides, and then recovers the valuable metals through conventional grinding and flotation. This method can realize the sulfidation conversion and recovery of the oxidation state of the valuable metals, but this method requires an additional 35 hours of standing after the hot copper slag is slowly cooled to room temperature, which prolongs the operation time, and the slow cooling speed of this method is too fast, which is significantly different from the actual large-scale copper smelting, and is difficult to industrialize; Chinese patent document CN105671326B (a method for depleting copper slag by stirring and coordinating gas with sulfiding agent) introduces an eccentric mechanical stirring device into the depletion furnace to heat and stir the copper slag, and at the same time uses a permeable brick to blow gas to introduce a sulfiding agent to recover the matte in the copper slag, but this method has high equipment requirements and the furnace The slag treatment volume is small and the copper recovery effect is limited; Chinese patent document CN118813968A (Application of sulfurizing conditioning agent in recovering valuable metals in copper slag) uses solid wastes such as gypsum slag and sodium sulfate waste salt to prepare sulfurizing conditioning agent with carbonaceous reducing agent, and directly adds hot slag for sulfurization transformation. This method is simple, but the addition of sulfurizing agent is too large, the system heat may be insufficient, and it has not yet explained the treatment method of cooled slag, and there are still certain differences and difficulties in industrial application; Chinese patent document CN109971967A (A method for recovering valuable metals from copper smelting and blowing slag) adds slag-making agent, copper concentrate, and reducing agent to the smelting furnace for smelting, and a cobalt matte melt and a slag melt can be obtained. The cobalt matte is subsequently slowly cooled and separated and recovered by magnetic separation. This method has a high metal recovery rate, but requires additional large-scale equipment and heat input, and the amount of reagents used is too large, which can easily cause an increase in the amount of slag.

[0005] Based on the copper smelting production practice and the characteristics of valuable component recovery in smelting slag, without changing the main process, without modifying the main equipment, and without affecting production continuity, a copper slag treatment method with reasonable design, low equipment investment and operating costs, and high comprehensive recovery rate of valuable metals has been developed by simultaneously utilizing the slag's own latent heat and physical and chemical properties. It has great scientific significance and application prospects. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a method for promoting the sedimentation of copper matte and the recovery of copper in slag, which has low cost, simple process, simple materials and is easy to realize industrial application.

[0007] In view of the above technical problems, the following solutions are proposed:

[0008] A method for self-heating tempering of copper smelting slag and zoned recovery of valuable metals, comprising:

[0009] S1. Mechanically mixing industrial sulfate waste and cheap carbonaceous reducing agent in proportion to prepare slag conditioning agent;

[0010] S2. During the copper smelting matte smelting and slag removal process, a tempering agent is added to the slag to perform slag autothermal tempering;

[0011] S3. After the molten slag is slowly cooled, the upper and lower parts of the materials in the slag bag are classified and processed, and the upper lean slag is discharged for conventional crushing, grinding, and flotation to recover valuable metals;

[0012] S4. The lower rich matte slag is directly returned to the smelting system or crushed and ground and then recovered through "magnetic separation-reverse flotation" to recover copper concentrate.

[0013] In this technical solution, sulfate waste refers to solid waste containing sulfate, such as mirabilite slag and gypsum slag, the main components of which are Na2SO4, CaSO4, etc., which react with the main component C in the carbonaceous reducing agent at high temperature to generate Na2S and CaS. The intermediate products Na2S and CaS further react with the metal oxides (Cu2O, Fe3O4, ZnO, PbO) in the slag to sulfide the valuable metals in the slag, which is convenient for subsequent flotation recovery. At the same time, whether it is Na2S, CaS, or Me after sulfide conversion x S (Me = Cu, Zn, Pb, Fe) can all act as sulfide seeds to induce matte aggregation, growth, and sedimentation in the slag, and form an obvious matte sedimentation layer at the bottom of the slag bag, completing the depletion in the slag bag.

[0014] Preferably, in step S1, the sulfate waste is one or more of industrial solid wastes whose main component is sulfate, which is a by-product generated in the process of sulfuric acid production, ore smelting, and chemical production, such as sodium sulfate residue, gypsum residue, etc.;

[0015] Preferably, in step S1, the carbonaceous reducing agent is one or more of biochar, charcoal, and activated carbon;

[0016] Preferably, in step S1, the mixing ratio is a mass ratio of sulfate slag to reducing agent of 2:1 to 10:1;

[0017] Preferably, in step S1, the matte making smelting and slag removal process is a step of matte making smelting in flash smelting, oxygen-enriched top blowing smelting, oxygen-enriched side blowing smelting, oxygen-enriched bottom blowing smelting and other processes;

[0018] Preferably, in step S1, the mixed material is in the form of powder, pellets, or blocks;

[0019] Preferably, in step S2, the mixed material is added to the slag by one or more of the following methods: directly pouring the mixed material into the bottom of the slag ladle before slag discharge, directly spraying the mixed material into the slag using an immersion spray gun in the smelting furnace before slag discharge, adding the mixed material into the slag in the chute using a heat-resistant pipe during slag discharge, bringing the mixed material into the slag during slag discharge, and directly spraying the mixed material into the slag using an immersion spray gun after slag discharge.

[0020] Preferably, in step S2, the amount of the mixed material added is 0.1% to 10% of the total amount of the copper slag;

[0021] Preferably, in step S2, the slag temperature is 1150°C to 1350°C;

[0022] Preferably, in step S3, the slow cooling system is matched with the slow cooling system of copper slag in existing copper smelting enterprises, which is about 0.1-5°C / min;

[0023] Preferably, in step S4, the magnetic field strength of the magnetic separation is 0.05T-1.0T;

[0024] Preferably, in step S4, the pH of the reverse flotation process is controlled at 8-12, the inhibitor is one or more of zinc sulfate or cyanide, with a dosage of 100-1000 g / t, the collector is one or more of oleic acid, tall oil, sulfonate, dodecylamine, and amine, with a dosage of 30-300 g / t; the frother is one or more of 2# oil or MIBC, with a dosage of 10-100 g / t.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) Existing methods for recovering copper from copper slag generally have the problems of large reagent consumption, the need for additional large-scale equipment, the need for additional heat and energy supplementation, and the high copper content in the tailings. At the same time, most of the methods are only laboratory exploratory research and do not have an industrial practice and application basis. The present invention provides a method for self-heating tempering and partition recovery of valuable metals in copper smelting slag. Based on the industrial foundation and industrial conditions, factory tests are directly carried out. In the process, industrial sulfate solid waste gypsum slag or mirabilite and cheap carbonaceous reducing agent are used as raw materials. During the slag discharge process, they are added to the slag bag with the molten slag. During the slow cooling process, the molten slag provides heat for the reduction and decomposition of the sulfate solid waste. The sulfate solid waste decomposes to generate corresponding sulfides Na2S and CaS. These sulfides react with the oxidized metals in the slag to achieve the sulfidation conversion of the valuable metals, which can be subsequently recovered by flotation. Different from the methods adopted in the prior art of adding new furnaces to separately treat slag and adding a large proportion of modifiers, this patent uses existing chutes to add a small amount of modifiers based on existing processes, existing equipment, and existing procedures, thereby achieving in-situ self-heating tempering of slag and recovery of valuable metals. It has the advantages of high metal recovery rate, low cost, environmental friendliness, simple process and materials, and low difficulty in industrialization. It has good economic and environmental benefits and is easy to promote and apply.

[0027] (2) Sulfate wastes such as mirabilite slag and gypsum slag are often industrial solid wastes, and some are even classified as hazardous solid wastes. The present invention uses copper smelting slag to extract valuable elements and solidify toxic elements. The invention provides a new solution for the digestion of the above-mentioned sulfate solid wastes.

[0028] (3) The failure of matte to be fully settled and the insufficient clarification and separation between matte and slag are one of the important reasons for the loss of copper in the slag. In the present invention, whether it is the intermediate product Na2S, CaS or the target product Me x S (Me = Cu, Zn, Pb, Fe) can be used as sulfide seeds to induce matte aggregation, growth and sedimentation in the slag. Therefore, after the slag bag is slowly cooled, a large amount of copper concentrate will settle in the lower part of the slag bag. At this time, the upper and middle parts of the slag bag are subjected to conventional crushing, grinding and flotation treatment, and the slag enriched with a large amount of copper concentrate in the lower part can be used to select oxide ore and gangue components through "magnetic separation-reverse flotation" to obtain copper concentrate, and can also be directly returned to the smelting system without flotation. Special treatments such as strengthening copper recovery in the slag effectively reduce the workload of slag grinding and improve the production efficiency of slag. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 It is a process flow chart of the present invention.

[0031] Figure 2 This is an optical photograph of the rich matte slag in the lower part of the slag ladle sampled in Example 1 of the present invention.

[0032] Figure 3 This is the XRD detection diagram of the upper and lower parts of the slag in Example 1 of the present invention.

[0033] Figure 4 This is the XRD detection diagram of the upper and lower parts of the slag in Example 2 of the present invention.

[0034] Figure 5 This is a diagram of the toxic leaching results of Example 2 of the present invention.

[0035] Figure 6 This is the XRD detection diagram of the upper and lower parts of the slag in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0036] In order to facilitate the understanding of the present invention, the present invention will be described in more comprehensive and detailed manner below in conjunction with the accompanying drawings and preferred embodiments of the specification, but the protection scope of the present invention is not limited to the following specific embodiments.

[0037] Example 1

[0038] A method for self-heating and tempering of copper smelting slag and recovery of valuable metals by different zones, the process flow chart is as follows: Figure 1 As shown, the following steps are included: Grind cheap reducing agent fruit wood charcoal and thenardite slag to -200μm, and evenly mix the two according to the mass ratio of thenardite slag to reducing agent of 6.15:1. During the process, ball milling equipment is used to enhance the mixing effect. The total mass of the mixed sample is about 80.0kg. After that, a field test was carried out in a domestic copper smelter. Each slag bag contained about 30 tons of copper slag, the slag temperature was about 1200℃, and the slag discharge time of each bag was about 25min. All materials were added during the slag discharge process. Afterwards, the slag bag containing the molten slag was transported to the slag yard by a slag truck. After 3 days of natural slow cooling, the slag was sprayed with cooling water for 2 days to complete the slow cooling of the slag. It was found that there was an obvious matte precipitation layer (i.e., matte-rich area) at the bottom. The optical photograph is shown in the figure. Figure 2 As shown in the figure, the slag bag is divided into three parts: the upper part is the upper 2 / 3 height area of ​​the slag bag, and the lower part is the lower 1 / 3 height area of ​​the slag bag. Samples are taken from the upper and lower parts respectively, and then the samples are tested by XRD. The results are shown in Figure 3 As shown in the figure, it can be seen that the upper and lower parts of the slag are mainly composed of fayalite and magnetite. In addition, there is obvious Cu 5.433 Fe 1.087The S4 diffraction peak further proves the aggregation and sedimentation of matte during the process. In order to clarify the concentrate content and copper enrichment in different parts, the upper and lower parts are still crushed and ground for ore dressing. During the ore dressing process, the grinding time is 50 minutes, the liquid-solid ratio is 1:2, and the final particle size is less than 0.045mm. The particles exceed 80%. The ground sample is floated, and the rapid flotation and roughing are 5 minutes each, and the two sweeps are 5 minutes and 3 minutes respectively. The collector and frother used in the process are butyl xanthate and pine oil respectively. The dosage of butyl xanthate in rapid flotation, roughing and two sweeps is 250g / t, 80g / t, 21g / t, 18g / t, and the dosage of pine oil in rapid flotation, roughing and the first sweep is 160g / t, 18g / t, and 6g / t.

[0039] After flotation, the weight and copper content of the concentrate, middlings and tailings were tested. The overall copper distribution of the slag can be calculated based on the weight and copper content of each part. The upper and lower copper distribution ratios are 17.71% and 82.29% respectively. The copper distribution ratio in the lower part of the slag bag exceeds 80% of the total copper, indicating that obvious copper enrichment occurred in the slag bag during the slow cooling process. By calculation, the comprehensive slag copper content is 0.19wt.%, and the comprehensive recovery rate is 98.8%.

[0040] Example 2

[0041] A method for recovering valuable metals from copper smelting slag by zoning and classification, the process flow chart is as follows: Figure 1 As shown, the following steps are included: grind the cheap reducing agent fruit wood charcoal and gypsum slag to -200μm, and mix the two uniformly according to the mass ratio of gypsum slag to reducing agent of 5.4:1. The total mass of the mixed sample is about 220.4kg. The operation is the same as that of Example 1, and the two slag bags in Examples 1 and 2 are continuously taken, and the sampling process is the same as that of Example 1. Afterwards, XRD detection is performed on the upper and lower samples in Example 2, and the results are as follows Figure 4 As shown in the figure, it can be seen that the upper and lower parts of the slag are mainly composed of fayalite and magnetite. In addition, there is also obvious Cu 5.433 Fe 1.087 The S4 diffraction peak proves the aggregation and sedimentation of copper matte during the process.

[0042] During the flotation process, the upper part is the same as Example 1, and the lower part adopts magnetic separation-reverse flotation, with a magnetic field strength of 0.50T. After obtaining non-magnetic minerals, flotation is performed. Flotation only performs roughing and concentrating, and the roughing pH is controlled to 8.5, the amount of zinc sulfate is 300g / t, the amount of oleic acid is 100g / t, the amount of MIBC is 30g / t, and the roughing time is 5min; the concentrating pH is controlled to 9, the amount of zinc sulfate is 100g / t, the amount of MIBC is 20g / t, and the concentrating time is 3min. After the ore dressing is completed, the weight and copper content of the concentrate, the middlings, and the tailings are tested. The upper and lower concentrates are 202.2g and 720.7g respectively, and the distribution ratio of copper concentrate is 21.9% and 78.1% respectively. It can be seen from the results that the lower concentrate content is higher and the upper part is less, indicating that matte aggregation, growth, and sedimentation also occur in the slag bag. By calculation, the comprehensive slag contains 0.17wt.% copper, and the comprehensive recovery rate is 99.0%. The tailings and gypsum slag raw materials were then subjected to TCLP toxicity leaching tests, and the results were as follows: Figure 5 As shown in the figure, it can be seen from the TCLP results that the toxic leaching of As and Cd in gypsum slag obviously exceeds the standard. However, after being added to the molten slag and slowly cooled, the toxic leaching results of the slag show that all elements do not exceed the standard, indicating that this technology can stably digest some hazardous wastes and alleviate environmental pressure.

[0043] Comparative Example 1

[0044] No additives were added to Comparative Example 1, and other operations were exactly the same as those in Example 1. The copper slag in Comparative Example 1 was from the same furnace as that in Examples 1 and 2. Three slag bags were continuously discharged. The sampling process was the same as that in Example 1, and there was no obvious stratification during the sampling process. Afterwards, XRD tests were performed on the upper and lower samples of Comparative Example 1, and the results were as follows: Figure 6 As shown in the figure, the difference from Examples 1 and 2 is that the upper and lower parts of the slag are mainly composed of fayalite and magnetite, but there is a weak Cu 5.433 Fe 1.087 The S4 diffraction peak shows that the matte is mainly present in the upper part of the slag during the slow cooling process, and no obvious aggregation or sedimentation occurs. After the same crushing and grinding and flotation treatment as in Example 1, the weight and copper content of the concentrate, middlings and tailings are tested, and it is found that the slag bag does not show obvious concentrate aggregation. After that, the copper distribution of each part is calculated, and there is no obvious enrichment. The final comprehensive slag contains 0.26wt.% copper, and the comprehensive recovery rate is 97.6%.

Claims

1. A method for autothermal tempering of copper smelting slag and zone recovery of valuable metals, characterized in that: The steps include: S1. Prepare slag conditioning agent by mixing industrial sulfate solid waste with cheap carbonaceous reducing agent; S2. During the copper smelting matte smelting and slag removal process, a tempering agent is added to the slag; S3, after the slag is slowly cooled, the materials in the slag bag are processed in different areas, and the upper slag is crushed, ground, and floated to recover valuable metals; S4. The lower slag is directly returned to smelting as raw material, or crushed and ground into powder and then recovered through "magnetic separation-reverse flotation" to recover copper concentrate.

2. The method for recovering valuable metals in copper smelting slag according to claim 1, characterized in that: In step S1, the sulfate waste is one or more of industrial solid wastes whose main component is sulfate, which is a by-product generated in the process of sulfuric acid production, ore smelting, and chemical production, such as sodium sulfate slag, gypsum slag, etc.

3. The method for recovering valuable metals in copper smelting slag by different zones according to claim 1, characterized in that: In the step S1, the carbonaceous reducing agent is one or more of biochar, charcoal, and anthracite.

4. The method for recovering valuable metals in copper smelting slag by different zones according to claim 1, characterized in that: In the step S1, the mixing ratio is a mass ratio of sulfate slag to reducing agent of 1:1 to 10:

1.

5. The method for recovering valuable metals in copper smelting slag by different zones according to claim 1, characterized in that: In step S2, the matte making, smelting and slag removal process is a step of the matte making and smelting link in processes such as flash smelting, oxygen-enriched top blowing smelting, oxygen-enriched side blowing smelting, and oxygen-enriched bottom blowing smelting.

6. The method for recovering valuable metals in copper smelting slag by different zones according to claim 1, characterized in that: In the step S2, the mixed material is in the form of powder, pellets, or blocks, or in a form of more than one of the following: and the added amount is 0.1% to 10% of the total amount of the copper slag.

7. The method for recovering valuable metals in copper smelting slag by different zones according to claim 1, characterized in that: In the step S2, the slag temperature is 1150°C to 1350°C.

8. The method for recovering valuable metals in copper smelting slag by different zones according to claim 1, characterized in that: In step S3, the slow cooling system is matched with the slow cooling system of copper slag in existing copper smelting enterprises, which is about 0.1-5°C / min.

9. The method for recovering valuable metals in copper smelting slag by different zones according to claim 1, characterized in that: In step S4, the magnetic field strength of the magnetic separation is 0.05T-1.0T.

10. The method for recovering valuable metals in copper smelting slag by different zones according to claim 1, characterized in that: In step S4, the pH of the reverse flotation process is controlled at 8-12, the inhibitor is one or more of zinc sulfate or cyanide, with a dosage of 100-1000 g / t, the collector is one or more of oleic acid, tall oil, sulfonate, dodecylamine, and amine, with a dosage of 30-300 g / t; the frother is one or more of 2# oil or MIBC, with a dosage of 10-100 g / t.

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