Method for efficiently recovering gold and silver from waste gold and silver smelting graphite crucible

Abstract

The invention provides a method for efficiently recycling gold and silver from waste gold and silver smelting graphite crucibles. The method comprises the steps that the waste graphite crucibles are classified, crushed and finely ground according to gold smelting and silver smelting, and crucible slag is obtained; the crucible slag is primarily selected and pre-enriched through a spiral chute, and pre-enriched slag and tailings are obtained; the pre-enriched slag is subjected to two-stage fine sand shaking table concentration to obtain gold / silver-enriched slag; adding an oxidizing agent into the gold / silver-rich slag to oxidize and roast to obtain ashed slag; performing high-temperature and high-pressure strong alkali leaching on the ashed slag to obtain alkali leaching slag; and alkaline leaching residues are leached with dilute acid to deeply remove impurities, and crude gold / silver powder with highly-enriched gold / silver is obtained. According to the method, the beneficiation and smelting combined process is adopted for deeply removing impurities and continuously enriching gold and silver, so that the problems of refractory pyrometallurgy, insufficient oxidizing roasting, gold robbing of carbonaceous substances leached by a wet method, high unit energy consumption or high water consumption and the like caused by huge amount of carbonaceous substance gangue in the traditional process for smelting the graphite crucible slag from the waste gold and silver are solved; and the recovery of gold and silver dispersed in the gaps of the waste gold and silver smelting graphite crucible is effectively realized.

Description

Technical Field

[0001] The invention belongs to the technical field of solid waste recycling, and in particular relates to a method for efficiently recovering gold and silver from a discarded gold and silver smelting graphite crucible. Background Art

[0002] The gold and silver metallurgical industry generally uses medium (high) frequency induction furnaces for gold and silver smelting, refining, and casting. High-density graphite crucibles, graphite clay crucibles, or graphite silicon carbide crucibles are generally used as melting furnaces. These crucibles are subject to mechanical scouring of gold and silver liquid, internal pressure, flux corrosion, high-temperature oxidation, etc. during use, causing the dense layer or glaze layer on the surface of the lining to gradually fall off, and the gold and silver molten liquid is dispersed into the pores or gaps on the crucible wall in the form of tiny particles. In gold and silver metallurgy, graphite, graphite clay, and graphite silicon carbide are all difficult-to-handle carbonaceous gangue components. During pyrometallurgical smelting, carbonaceous materials will greatly increase the melting point of the slag, affect the fluidity of the slag, and reduce the metal recovery rate. During wet extraction, because carbonaceous materials have a strong "gold robbery" effect, a small amount of carbon, especially organic carbon, will greatly reduce the gold and silver leaching rate. Therefore, in theory, gold and silver raw materials containing carbonaceous materials are usually subjected to oxidative roasting to oxidize the carbonaceous materials, thereby eliminating the adverse effects of the high melting point of the carbonaceous materials on pyrometallurgy and the "gold robbing" effect on hydrometallurgy.

[0003] At present, there are few studies or applications on the recovery of gold, silver or other valuable metals from abandoned graphite crucibles in metal smelting. CN108823416B discloses a method for extracting gold and silver from clay graphite crucible slag, wherein the crucible slag is first reacted with a sulfuric acid / fluorosilicic acid mixture, then calcined at 900-1000°C, and finally separated from the gold and silver by acid and aqua regia leaching, respectively. CN109055767A discloses a method for extracting gold and silver from clay graphite crucible slag by alkali roasting, wherein the method is directed to the same crucible slag as that in CN108823416B, and then separated from the gold and silver by acid and aqua regia leaching, respectively. However, both of the above methods are directly used for a large amount of graphite clay crucible slag, and either wet method or pyrolysis is used for impurity removal first. The impurity removal effect is not good, with the highest impurity removal rate being only 42.69%. Moreover, wet method produces a large amount of wastewater, while pyrolysis consumes a lot of energy. In addition, the amount of enriched slag after impurity removal is still large. At this time, direct silver nitrate separation and water regia gold separation will cause the existence of incompletely oxidized carbonaceous materials to "rob gold". On the other hand, the practice of gold and silver production shows that trace amounts of gold and silver (impurity content is as high as 99.95%) are difficult to be effectively recovered by water regia gold separation or silver nitric acid separation, and there is still a lot of gold and silver residue in the gold separation slag and silver separation slag.

[0004] Regarding the recovery of gold and silver from abandoned gold and silver smelting graphite crucibles, if the crushed graphite crucible slag is directly smelted, it will be difficult to melt due to the high graphite content (graphite melting point 3652℃); if the crucible slag is completely oxidized and roasted, there will be problems such as large roasting processing volume, low ashing efficiency, insufficient oxidation, and high unit energy consumption; if a wet process is used, it is difficult to effectively recover relatively low gold and silver from a large amount of graphite carbon powder due to the "gold robbing" effect of carbonaceous materials; if a conventional pyrometallurgical-wet combined process is used, there will be common problems faced by both methods. Therefore, under the existing process equipment conditions, gold and silver smelting enterprises have almost no effective method to systematically recover the dispersed gold and silver in abandoned gold and silver smelting crucibles.

[0005] In order to recover some of the gold and silver scattered in the abandoned gold and silver smelting graphite crucible, usually only the surface of the inner wall of the crucible can be manually cleaned and a small amount of gold and silver can be washed and recovered. Most of the scattered gold and silver still remain in the crucible wall, containing up to 200~450g / t of gold or silver. These gold and silver scattered in the crucible wall can only be sold to non-ferrous smelters together with the crucible after being converted at a low valuation factor of 10%~25% for gold and 5%~10% for silver, and then used in small amounts as a reduction smelting additive to gradually recover the scattered and lost gold and silver. However, for gold and silver smelting enterprises, this method has a total recovery rate of only 5%~25% for gold or silver, and gold and silver cannot be effectively recycled, resulting in the loss of valuable resources.

[0006] In order to solve the shortcomings of the existing method for recovering dispersed gold and silver in abandoned gold and silver smelting graphite crucibles, the present invention provides a method for efficiently recovering gold and silver from abandoned gold and silver smelting graphite crucibles which is efficient, simple, economically feasible, environmentally friendly and highly adaptable. Summary of the invention

[0007] In view of the above problems, the present invention provides a method for efficiently recovering gold and silver from abandoned graphite crucibles for gold and silver smelting. According to the principle of continuous enrichment of precious metal extraction, a large amount of impurity components such as graphite are deeply removed by a combined selection and smelting process to obtain highly enriched gold and silver products that are convenient for conventional refining and purification processes, thereby achieving efficient recovery of gold and silver lost in dispersed forms in abandoned crucibles for gold and silver smelting.

[0008] To achieve the above objectives, the present invention adopts the following technical solutions: A method for efficiently recovering gold and silver from an abandoned gold and silver smelting graphite crucible comprises the following steps: (1) Crucible classification pretreatment, crushing and fine grinding: Gold and silver are recovered according to the crucibles for gold smelting and silver smelting. The gold or silver attached to the inner wall of the gold or silver smelting crucible is cleaned out and transferred to a sand blasting machine for wet crushing (crushing while spraying water to reduce dust). The crushed slag is sent to a ball mill for fine grinding to obtain crucible slag; (2) Pre-enrichment in spiral chute: The crucible slag obtained in step (1) is slurried and sent to the spiral chute for preliminary selection to remove most of the graphite, carbon powder and other substances. The spiral chute concentrate and middlings obtained are the pre-enrichment slag, and the spiral chute tailings are sold externally; (3) Two-stage fine sand shaking table selection: the pre-enriched slag obtained in step (2) is sent to the first-stage shaking table for selection, and the obtained first-stage concentrate and middlings are sent to the second-stage shaking table for reselection. The produced second-stage concentrate is gold-rich slag or silver-rich slag, and the second-stage middlings are returned to the first-stage shaking table for reselection to further recover gold and silver. The tailings of the two-stage shaking tables are sold out; (4) Oxidation roasting and ashing of gold-rich or silver-rich slag: drying the gold-rich or silver-rich slag obtained in step (3), adding potassium nitrate and sending it to a muffle furnace for oxidation roasting to fully ashed the carbonaceous matter and other substances to obtain ashed slag; (5) High temperature and high pressure strong alkali leaching: The ash residue obtained in step (4) is added to a sodium hydroxide solution, a small amount of potassium nitrate is added, and the mixture is introduced into a high pressure autoclave for high temperature and high pressure leaching, so that the acidic mud such as SiO2 and Al2O3 in the residue is dissolved as much as possible, and the alkali leaching residue is separated; (6) Deep impurity removal by dilute acid leaching: The alkaline leaching residue obtained in step (5) is leached with dilute hydrochloric acid to allow all metal oxides such as CaO, Fe2O3, MgO, and K2O to enter the solution. The crude gold powder or the crude silver powder is filtered out and incorporated into the aqua regia gold purification process. The crude silver powder is melted into anode plates and incorporated into the electrolytic silver refining process.

[0009] Preferably, the ball mill fine grinding time in step (1) is 1.5 to 3 hours, and the crucible slag particle size of -0.074 mm accounts for more than 85%.

[0010] Preferably, the spiral chute in step (2) is a single-head chute with a cross-sectional width of 25 to 30 cm, a lateral inclination of 9 to 12°, 5 to 8 blades, a feed rate of 200 to 300 kg / h, and a feed concentration of 15% to 25%. The interception valve adjusts the interception range according to the distribution of the concentrate and middling ore zones.

[0011] Preferably, the shaking table in step (3) is a two-stage fine sand shaking table with a screen surface of 60 to 88 slots, a lateral slope of 1.5 to 3.5°, a longitudinal slope of 0.5 to 1.5°, a feed rate of 100 to 200 kg / h, a feed concentration of 25% to 35%, and a flushing water rate of 15 to 35 L / min; wherein the first-stage shaking table has a stroke of 12 to 15 mm and a stroke of 250 to 280 times / min, and the second-stage shaking table has a stroke of 8 to 12 mm and a stroke of 300 to 340 times / min.

[0012] Preferably, in step (4), potassium nitrate is added at 2% to 5% of the weight of the gold-rich slag and mixed evenly, with a thickness of 0.5 to 2.0 cm, and roasted for 3 to 6 hours in a muffle furnace at an operating temperature of 600 to 900° C. and with the furnace door open 2 to 5 cm.

[0013] Preferably, in step (5), the ashing slag is mixed with a sodium hydroxide solution having a concentration of 2 to 5 mol / L at a liquid-to-solid ratio of 4:1 to 6:1, and potassium nitrate in an amount of 1.0% to 2.5% by weight of the ashing slag is added as a catalyst, and the mixture is introduced into an autoclave to control the total pressure in the reactor to 2.0 to 5.0 MPa, the oxygen partial pressure to 0.1 to 0.5 MPa, the reaction temperature to 140 to 180° C., and the reaction time to 1 to 2.5 h, and then the mixture is cooled, filtered, and washed to obtain the alkaline leached slag.

[0014] Preferably, in step (6), the alkaline leaching residue is mixed with dilute hydrochloric acid with a molar mass of 3 to 5 mol / L at a liquid-to-solid ratio of 2:1 to 5:1, the temperature is controlled at 50 to 70° C., the stirring speed is 200 to 300 r / min, the reaction time is 1 to 2 h, and the crude gold powder or crude silver powder is obtained by suction filtration and washing.

[0015] Beneficial effects of the present invention: (1) The present invention adopts a combined metallurgical process to deeply remove a large amount of impurity components such as graphite in the gold and silver smelting crucible slag, thereby obtaining highly enriched gold and silver products that are convenient for conventional refining and purification processes, effectively solving the problem that gold and silver smelting enterprises were previously unable to efficiently recover dispersed gold and silver from abandoned gold and silver smelting graphite crucibles.

[0016] (2) The present invention utilizes the characteristic that the density of gold and silver is much greater than that of graphite powder to perform gravity separation and impurity removal. The impurity removal rate is as high as 95.29%, the gold and silver enrichment ratio can reach 110 times, and the separation effect is remarkable. It solves the problems of difficult melting in pyrometallurgy, insufficient oxidation roasting, "gold robbing" of carbonaceous materials by wet leaching, high unit energy consumption or large water consumption caused by the huge amount of carbonaceous gangue in the abandoned gold and silver smelting graphite crucible slag in the traditional process, and obtains the preliminary enriched gold and silver that is easy to be processed by metallurgical process.

[0017] (3) According to the principle of continuous enrichment of precious metal extraction, the present invention adopts oxidative roasting ashing, high temperature and high pressure alkaline leaching and acid leaching to further remove impurities in depth, with an impurity removal rate of up to 98.53%, a cumulative enrichment of gold of 2560 times, a cumulative enrichment of silver of 1897 times, a comprehensive recovery rate of gold increased from 10% to 25% to 92.89%, and a comprehensive recovery rate of silver increased from 5% to 10% to 88.62%, effectively realizing efficient recovery of gold and silver, with significant economic benefits.

[0018] (4) The combined metallurgical process of the present invention is efficient, simple, adaptable, environmentally friendly, and economically feasible, and has extensive reference and promotion value for gold and silver smelting enterprises to recover gold and silver from carbonaceous resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The present invention is a process flow diagram of a method for efficiently recovering gold and silver from an abandoned gold and silver smelting graphite crucible. DETAILED DESCRIPTION

[0020] In order to make the technical problems and technical solutions solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0021] like Figure 1 A method for efficiently recovering gold and silver from an abandoned gold and silver smelting graphite crucible is shown, and the specific steps include: (1) Crucible classification, pretreatment, crushing and fine grinding: Gold and silver are recovered according to the crucibles for gold smelting and silver smelting. The gold (silver) attached to the inner wall of the gold (silver) smelting crucible is cleaned with a spatula, and then crushed in a hammer sand blaster while sprinkling water (sprinkling water to reduce dust). The crushed slag is sent to a ball mill for fine grinding for 1.5 to 3 hours to obtain crucible slag with a particle size of -0.074 mm accounting for more than 85%. After being fully mixed several times, it is spread flat to a slag layer of about 3 cm thick for repeated sampling and analysis of gold (silver) and major impurity components.

[0022] (2) Pre-enrichment in spiral chute: The crucible slag and water are mixed in a weight ratio of 1:3 to 1:6, and then introduced into the distribution box at the top of the spiral chute. The speed of the stirring paddle in the box is 300r / min. The opening of the valve at the bottom of the box is controlled to make the slag swirl from top to bottom. The feed rate is 200-300kg / h. The lateral inclination of the chute is 9-12°, and the number of blades is 5. The interception valve at the end of the chute adjusts the interception range according to the distribution of the concentrate and the middling ore. The mixture of the spiral concentrate and the middling ore is the pre-enrichment slag. The tailings are filtered and dried to obtain the spiral chute tailings for sale, and the filtrate and tailings are discharged into the sedimentation tank for reuse.

[0023] (3) Two-stage fine sand shaking table selection: The pre-enriched slag is sent to the first-stage shaking table for sorting. The first-stage shaking table screen surface has 60 to 88 slots, a horizontal slope of 1.5 to 3.5°, a longitudinal slope of 0.5 to 1.5°, a stroke of 12 to 15 mm, a flushing frequency of 250 to 280 times / min, a feed rate of 100 to 200 kg / h, a feed concentration of 25% to 35%, and a flushing water of 15 to 35 L / min to obtain primary concentrate, middlings and tailings; The primary concentrate and middlings are sent to the secondary shaking table for re-selection. The secondary shaking table has a screen surface of 60 to 88 slots, a horizontal slope of 1.5 to 3°, a longitudinal slope of 0.5 to 1.5°, a stroke of 8 to 12 mm, a flushing frequency of 300 to 340 times / min, a feed rate of 100 to 150 kg / h, a feed concentration of 20% to 30%, and a flushing water of 15 to 20 L / min. Secondary concentrate, middlings and tailings are obtained. The secondary concentrate is filtered and dried to obtain gold (silver)-rich slag. The secondary middlings are returned to the primary shaking table for re-selection. The primary tailings are mixed with the secondary tailings, filtered and dried to obtain the shaking table tailings for sale, and the filtrate and tailings are discharged into the sedimentation tank for reuse.

[0024] (4) Oxidation roasting and ashification of gold (silver) rich slag: Add potassium nitrate according to 2% to 5% of the weight of the gold (silver) rich slag and mix well. Spread it to a thickness of 0.5 to 2.0 cm. Roast it for 3 to 6 hours in a muffle furnace with an operating temperature of 600 to 900°C and the furnace door open 2 to 5 cm to obtain ash slag.

[0025] (5) High temperature and high pressure strong alkali leaching: The ash residue is mixed with a sodium hydroxide solution with a concentration of 2 to 5 mol / L at a liquid-to-solid ratio of 4:1 to 6:1, and potassium nitrate is added as a catalyst at a weight of 1.0% to 2.5% of the ash residue. The mixed liquid is introduced into a stainless steel high-pressure reactor. The total pressure in the reactor is controlled at 2.0 to 5.0 MPa, the oxygen partial pressure is controlled at 0.1 to 0.5 MPa, the reaction temperature is controlled at 140 to 180°C, and the reaction time is controlled at 1 to 2.5 h. The alkali leaching residue is cooled, filtered, and washed to obtain the alkali leaching residue, and the filtrate is discharged into the wastewater pool.

[0026] (6) Deep impurity removal by dilute acid leaching: The alkaline leaching residue is mixed with dilute hydrochloric acid with a molar mass of 3 to 5 mol / L at a liquid-to-solid ratio of 2:1 to 5:1. The temperature is controlled at 50 to 70 °C, the stirring speed is 200 to 300 r / min, and the reaction time is 1 to 2 h. The crude gold or silver powder is obtained by suction filtration and washing, and the filtrate is discharged into the wastewater pool.

[0027] In particular, the composition range of the waste gold and silver smelting graphite crucible slag used in the embodiment of the present invention is described as follows: (1) The main components of gold smelting crucible slag are: Au 248.41 g / t, C 76.46%, SiO2 7.62%, Al2O32.06%, CaO 5.56%, Fe2O3 0.74%, MgO 1.69%, K2O 0.42%, H2O 4.33%, and others <1.12%.

[0028] (2) The main components of silver smelting crucible slag are: Ag 373.84 g / t, C 75.03%, SiO2 9.41%, Al2O32.49%, CaO 5.89%, Fe2O3 0.53%, MgO 1.75%, K2O 0.23%, H2O 3.86%, and others <0.81%. Example 1

[0029] This embodiment adopts a method for efficiently recovering gold and silver from a discarded gold and silver smelting graphite crucible provided by the present invention to recover gold in the above-mentioned "gold smelting crucible slag", which specifically includes the following steps: (1) Weigh 200.00 kg of gold smelting crucible slag and add 0.8 m of water. 3After mixing, the slurry swirls from top to bottom on the spiral chute at a flow rate of 20L / min to obtain a mixture of spiral chute concentrate and middlings as pre-enriched slag. The tailings are filtered and dried to obtain 121.64Kg of spiral chute tailings with a gold content of 16.92g / t.

[0030] (2) The pre-enrichment slag was slurried with 200L of water and then sent to the first-level shaking table for separation, with a feed rate of 100Kg / h and a flushing water rate of 25L / min. The first-level concentrate and middlings were slurried with 50L of water and then sent to the second-level shaking table for re-separation, with a feed rate of 100 kg / h and a flushing water rate of 16L / min. The obtained second-level concentrate was filtered and dried to obtain 1770.52g of gold-rich slag with a gold content of 2.61%; the second-level middlings were returned to the first-level shaking table for re-separation, and the tailings of the two-level shaking tables were mixed, filtered, and dried to obtain 56.28kg of shaking table tailings with a gold content of 10.33g / t.

[0031] (3) Add 50 g of potassium nitrate to the gold-rich slag, mix well, spread it evenly to a thickness of 1.0 cm, and roast it in a muffle furnace at a constant temperature of 760°C for 4 h, keeping the furnace door open by 3 cm, to obtain 581.02 g of ashing slag.

[0032] (4) The above-mentioned ash slag was mixed with 2.4L of 5mol / L sodium hydroxide solution, and 15g of potassium nitrate was added. The mixture was introduced into a stainless steel high-pressure reactor. The total pressure in the reactor was controlled to be 3.5Mpa, the oxygen partial pressure was 0.4Mpa, the reaction temperature was 180°C, and the reaction time was 2h. After the reaction was completed, the slag was cooled, filtered, and washed to obtain an alkaline leached residue with a drying weight of 301.18g.

[0033] (5) The above alkaline leaching residue was added into 1.5L of 4mol / L hydrochloric acid solution, and the reaction temperature was controlled at 60°C in a glass reactor. The reaction was continued for 1h, and 76.34g of crude gold powder was obtained by filtration, with a gold content of 60.45%. The crude gold powder can be easily separated and purified by the Aqueous Regia Gold Extraction Method to recover gold.

[0034] Test results: The removal rate of graphite and other impurities in gold smelting crucible slag reached 93.85% under the combined separation of spiral chute and two-stage fine sand shaker, gold enrichment was 105 times, gold direct recovery rate was 92.91%, and the separation effect was significant; the gold-rich slag was enhanced to remove impurities, the impurity removal rate reached 98.25%, and the coarse gold powder obtained contained 60.45% gold; the cumulative gold enrichment of the whole process was 2434 times, and the comprehensive gold recovery rate was 92.89%, which effectively achieved the deep removal of impurities such as graphite in the discarded crucibles of gold smelting and the high enrichment and efficient recovery of gold. Example 2

[0035] This embodiment adopts a method for efficiently recovering gold and silver from a discarded gold and silver smelting graphite crucible provided by the present invention to recover gold in the above-mentioned "gold smelting crucible slag", which specifically includes the following steps: (1) Weigh 200.00 kg of gold smelting crucible slag and add 1.2 m of water.3 After mixing, the slag slurry swirls from top to bottom on the spiral chute at a flow rate of 30L / min to obtain a mixture of spiral chute concentrate and middlings as pre-enriched slag; the tailings are filtered and dried to obtain 132.29kg of spiral chute tailings with a gold content of 25.81g / t.

[0036] (2) The pre-enriched slag was slurried with 150L of water and then sent to the first-level shaking table for separation, with a feed rate of 150kg / h and a flushing water rate of 30L / min. The first-level concentrate and middlings were slurried with 40L of water and then sent to the second-level shaking table for re-separation, with a feed rate of 100kg / h and a flushing water rate of 20L / min. The obtained second-level concentrate was filtered and dried to obtain 1562.74g of gold-rich slag with a gold content of 2.75%. The second-level middlings were returned to the first-level shaking table for re-separation, and the tailings of the two-level shaking tables were mixed, filtered, and dried to obtain 50.37Kg of shaking table tailings with a gold content of 13.57g / t.

[0037] (3) Add 40 g of potassium nitrate to the gold-rich slag, mix well, spread evenly to a thickness of 1.0 cm, and roast in a muffle furnace at a constant temperature of 800°C for 3.5 h with the furnace door kept open by 4 cm to obtain 547.15 g of ashing slag.

[0038] (4) The above-mentioned ash slag was mixed with 2.2L of 5mol / L sodium hydroxide solution, and 10g of potassium nitrate was added. The mixture was introduced into a stainless steel high-pressure reactor. The total pressure in the reactor was controlled to be 3.2Mpa, the oxygen partial pressure was 0.3Mpa, the reaction temperature was 160°C, and the reaction time was 2h. After the reaction was completed, the slag was cooled, filtered, and washed to obtain an alkaline leached residue with a drying weight of 293.36g.

[0039] (5) The above alkaline leaching residue was added into 1.5L of 4.2mol / L hydrochloric acid solution, and the reaction temperature was controlled at 60°C in a glass reactor. The reaction was continued for 1h, and 72.09g of crude gold powder was obtained by filtration, with a gold content of 59.19%. The crude gold powder can be easily separated and purified by the Aqueous Regia Gold Extraction Method to recover gold.

[0040] Test results: The removal rate of graphite and other impurities in gold smelting crucible slag reached 95.29% under the combined separation of spiral chute and two-stage fine sand shaker, the gold enrichment ratio was 110 times, the gold direct recovery rate was 86.49%, and the separation effect was remarkable; the gold-rich slag was enhanced to remove impurities, the impurity removal rate reached 95.39%, and the coarse gold powder obtained contained 59.19% gold; the cumulative gold enrichment of the whole process was 2383 times, and the comprehensive gold recovery rate was 85.89%, which effectively achieved the deep removal of impurities such as graphite in the discarded crucibles of gold smelting and the high enrichment and efficient recovery of gold. Example 3

[0041] This embodiment adopts a method for efficiently recovering gold and silver from a discarded gold and silver smelting graphite crucible provided by the present invention to recover gold in the above-mentioned "gold smelting crucible slag", which specifically includes the following steps: (1) Weigh 316.52 kg of gold smelting crucible slag and add 1.5 ml of water. 3 After mixing, the slag slurry swirls from top to bottom on the spiral chute at a flow rate of 25L / min to obtain a mixture of spiral chute concentrate and middlings as pre-enriched slag; the tailings are filtered and dried to obtain 196.87kg of spiral chute tailings with a gold content of 18.79g / t.

[0042] (2) The pre-enriched slag was slurried with 300L of water and then sent to the first-level shaking table for separation, with a feed rate of 120kg / h and a flushing water rate of 25L / min. The first-level concentrate and middlings were slurried with 60L of water and then sent to the second-level shaking table for re-separation, with a feed rate of 100kg / h and a flushing water rate of 20L / min. The obtained second-level concentrate was filtered and dried to obtain 2809.68g of gold-rich slag with a gold content of 2.52%; the second-level middlings were returned to the first-level shaking table for re-separation, and the tailings of the two-level shaking tables were mixed, filtered, and dried to obtain 82.90Kg of shaking table tailings with a gold content of 8.85g / t.

[0043] (3) Add 80 g of potassium nitrate to the gold-rich slag, mix well, spread it evenly to a thickness of 1.0 cm, and roast it in a muffle furnace at a constant temperature of 700 °C for 3.5 h with the furnace door kept open by 4 cm to obtain 958.66 g of ashing slag.

[0044] (4) The above-mentioned ash slag was mixed with 4L of 5mol / L sodium hydroxide solution, and 15g of potassium nitrate was added. The mixture was introduced into a stainless steel high-pressure reactor. The total pressure in the reactor was controlled to be 4.0Mpa, the oxygen partial pressure was 0.4Mpa, the reaction temperature was 180°C, and the reaction time was 2.5h. After the reaction was completed, the alkali leaching residue was obtained by cooling, filtering, and washing. The dried residue weighed 472.78g.

[0045] (5) The above alkaline leaching residue was added into 2.0L of 4.5mol / L hydrochloric acid solution, and the reaction temperature was controlled at 70°C in a glass reactor. The reaction was continued for 1h, and 110.89g of crude gold powder was obtained by filtration, with a gold content of 63.59%. The crude gold powder can be easily separated and purified by the Aqueous Regia Gold Extraction Method to recover gold.

[0046] Test results: The removal rate of graphite and other impurities in gold smelting crucible slag reached 93.75% under the combined separation of spiral chute and two-stage fine sand shaker, gold enrichment was 101 times, gold direct recovery rate was 89.69%, and the separation effect was remarkable; the gold-rich slag was enhanced to remove impurities, the impurity removal rate reached 98.53%, and the coarse gold powder obtained contained 63.59% gold; the cumulative gold enrichment of the whole process was 2560 times, and the comprehensive gold recovery rate was 89.69%, which effectively achieved the deep removal of impurities such as graphite in the abandoned crucible of gold smelting and the high enrichment and efficient recovery of gold. Example 4

[0047] This embodiment adopts a method for efficiently recovering gold and silver from a discarded gold and silver smelting graphite crucible provided by the present invention to recover silver in the above-mentioned "silver smelting crucible slag", which specifically includes the following steps: (1) Weigh 300.00 kg of silver smelting crucible slag and add 1.5 ml of water. 3 After mixing, the slag slurry swirls from top to bottom on the spiral chute at a flow rate of 25L / min to obtain a mixture of spiral chute concentrate and middlings as pre-enriched slag; the tailings are filtered and dried to obtain 179.89 kg of spiral chute tailings, containing 32.57g / t silver.

[0048] (2) The pre-enrichment slag was added with 300L of water and sent to the first-stage shaking table for separation, with a feed rate of 100kg / h and a water rate of 20L / min. The first-stage concentrate and middlings were added with 70L of water for slurry preparation and sent to the second-stage shaking table for re-separation, with a feed rate of 100kg / h and a water rate of 18L / min. The obtained second-stage concentrate was filtered and dried to obtain 2994.73g of silver-rich slag with a silver content of 3.21%; the second-stage middlings were returned to the first-stage shaking table for re-separation, and the tailings of the two-stage shaking tables were mixed, filtered, and dried to obtain 94.60Kg of shaking table tailings with a silver content of 16.74g / t.

[0049] (3) Add 80 g of potassium nitrate to the above silver-rich slag, mix well, spread it evenly to a thickness of 1.0 cm, and roast it in a muffle furnace at a constant temperature of 750°C for 4 h with the furnace door kept open by 4 cm to obtain 1032.39 g of ashing slag.

[0050] (4) The above-mentioned ash slag was mixed with 4.5L of 5mol / L sodium hydroxide solution, and 20g of potassium nitrate was added. The mixture was introduced into a stainless steel high-pressure reactor. The total pressure in the reactor was controlled to be 4.0Mpa, the oxygen partial pressure was 0.4Mpa, the reaction temperature was 180°C, and the reaction time was 2.5h. After the reaction was completed, the slag was cooled, filtered, and washed to obtain an alkaline leached residue with a drying weight of 526.53g.

[0051] (5) The above alkaline leaching residue was added into 2.0L of 4 mol / L hydrochloric acid solution, and the reaction temperature was controlled at 70°C in a glass reactor. The reaction was carried out for 1h, and 134.71g of crude silver powder was obtained by filtration, containing 70.93% silver. The crude silver powder can be directly melted into anode plates for electrolysis to purify and recover silver.

[0052] Test results: The removal rate of graphite and other impurities in silver smelting crucible slag reached 95.17% under the combined separation of spiral chute and two-stage fine sand shaker, the silver enrichment ratio was 88 times, the silver direct recovery rate was 91.58%, and the separation effect was significant; the silver-rich slag was enhanced to remove impurities, the impurity removal rate reached 95.50%, and the crude silver powder contained 70.93% silver; the cumulative silver enrichment in the whole process was 1897 times, and the comprehensive silver recovery rate was 88.62%, which effectively achieved the deep removal of impurities such as graphite in the discarded crucibles of silver smelting and the high enrichment and efficient recovery of silver. Example 5

[0053] This embodiment adopts a method for efficiently recovering gold and silver from a discarded gold and silver smelting graphite crucible provided by the present invention to recover silver in the above-mentioned "silver smelting crucible slag", which specifically includes the following steps: (1) Weigh 400.00 kg of silver smelting crucible slag and add 1.6 m of water. 3 After mixing, the slag slurry swirls from top to bottom on the spiral chute at a flow rate of 30L / min to obtain a mixture of spiral chute concentrate and middlings as pre-enriched slag; the tailings are filtered and dried to obtain 246.51kg of spiral chute tailings, containing 36.22g / t of silver.

[0054] (2) The pre-enrichment slag was added with 320L of water and sent to the first-stage shaking table for separation, with a feed rate of 100kg / h and a water rate of 25L / min. The first-stage concentrate and middlings were added with 80L of water for slurry preparation and sent to the second-stage shaking table for re-separation, with a feed rate of 100kg / h and a water rate of 20L / min. The obtained second-stage concentrate was filtered and dried to obtain 3714.64g of silver-rich slag with a silver content of 3.43%. The second-stage middlings were returned to the first-stage shaking table for re-separation, and the tailings of the two-stage shaking tables were mixed, filtered, and dried to obtain 117.45Kg of shaking table tailings with a silver content of 17.26g / t.

[0055] (3) Add 100 g of potassium nitrate to the above silver-rich slag, mix well, spread it evenly to a thickness of 1.0 cm, and roast it in a muffle furnace at a constant temperature of 700°C for 4 h with the furnace door kept open by 4 cm to obtain 1173.13 g of ashing slag.

[0056] (4) The above-mentioned ash slag was mixed with 5L of 5mol / L sodium hydroxide solution, and 25g of potassium nitrate was added. The mixture was introduced into a stainless steel high-pressure reactor. The total pressure in the reactor was controlled to be 3.75Mpa, the oxygen partial pressure was 0.35Mpa, the reaction temperature was 180°C, and the reaction time was 2.5h. After the reaction was completed, the slag was cooled, filtered, and washed to obtain an alkaline leached residue with a drying weight of 725.94g.

[0057] (5) The alkaline leaching residue was added into 2.5 L of 4 mol / L hydrochloric acid solution, and the reaction temperature was controlled at 70°C in a glass reactor. The reaction was carried out for 1 h, and 184.61 g of crude silver powder was obtained by filtration, containing 68.42% silver. The crude silver powder can be directly melted into anode plates for electrolysis to purify and recover silver.

[0058] Test results: The removal rate of graphite and other impurities in crucible slag reached 94.64% under the combined separation of spiral chute and two-stage fine sand shaking table, silver was enriched 95 times, and the direct recovery rate of silver was 91.58%, with significant separation effect; the silver-rich slag was enhanced to remove impurities, with an impurity removal rate of 95.03%, and the crude silver powder obtained contained 68.42% silver; the cumulative silver enrichment in the whole process was 1830 times, and the comprehensive silver recovery rate was 87.86%, which effectively achieved the deep removal of impurities such as graphite in the discarded crucibles of silver smelting and the high enrichment and efficient recovery of silver.

[0059] It can be seen from the test results of Examples 1 to 5 that the method for treating the discarded graphite crucible for gold and silver smelting can effectively recover the gold and silver lost in the inner wall of the gold and silver smelting crucible, and the gold recovery rate is increased from 10% to 25% of the original price for sale to 92.89%. The obtained crude gold powder contains 63.59% gold, and the gold is enriched by 2560 times. The subsequent water regia gold metallization method can be used to efficiently purify and recover the gold; the silver recovery rate is increased from 5% to 10% of the original price for sale to 88.62%, and the obtained crude silver powder contains 70.93% silver, and the silver is enriched by 1897 times, and the anode plate can be directly melted and cast for electrolysis to purify and recover the silver.

[0060] The present invention is described in detail above through specific and preferred embodiments, but those skilled in the art should understand that the present invention is not limited to the embodiments described above, and any modifications, equivalent substitutions, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for efficiently recovering gold and silver from abandoned gold and silver smelting graphite crucibles, characterized in that: The following steps are involved: (1) Crucible classification pretreatment, crushing and fine grinding: gold and silver are recovered according to the crucibles for gold smelting and silver smelting. The gold or silver attached to the inner wall of the gold or silver smelting crucible is cleaned out and transferred to a sand blasting machine for wet crushing. The crushed slag is sent to a ball mill for fine grinding to obtain crucible slag; (2) Pre-enrichment in spiral chute: The crucible slag obtained in step (1) is slurried and sent to the spiral chute for preliminary selection to remove most of the graphite, carbon powder and other substances. The spiral chute concentrate and middlings obtained are the pre-enrichment slag, and the spiral chute tailings are sold externally; (3) Two-stage fine sand shaking table selection: the pre-enriched slag obtained in step (2) is sent to the first-stage shaking table for selection, and the obtained first-stage concentrate and middlings are sent to the second-stage shaking table for reselection. The produced second-stage concentrate is gold-rich slag or silver-rich slag, and the second-stage middlings are returned to the first-stage shaking table for reselection to further recover gold and silver. The tailings of the two-stage shaking tables are sold out; (4) Oxidation roasting and ashing of gold-rich or silver-rich slag: drying the gold-rich or silver-rich slag obtained in step (3), adding potassium nitrate and sending it to a muffle furnace for oxidation roasting to fully ashed the carbonaceous matter and other substances to obtain ashed slag; (5) High temperature and high pressure strong alkaline leaching: the ash residue obtained in step (4) is added to a sodium hydroxide solution, a small amount of potassium nitrate is added, and the mixture is introduced into a high pressure autoclave for high temperature and high pressure leaching to dissolve the acidic mud in the residue as much as possible, and the alkaline leached residue is separated; (6) Deep impurity removal by dilute acid leaching: The alkaline leaching residue obtained in step (5) is leached with dilute hydrochloric acid to allow all metal oxides to enter the solution. The crude gold powder or the crude silver powder is filtered to obtain the crude gold powder. The crude gold powder is incorporated into the aqua regia gold purification process. The crude silver powder is melted into anode plates and incorporated into the electrolytic silver refining process.

2. The method for efficiently recovering gold and silver from abandoned gold and silver smelting graphite crucible according to claim 1, characterized in that: The ball mill fine grinding time in step (1) is 1.5 to 3 hours, and the crucible slag particle size of -0.074 mm accounts for more than 85%.

3. The method for efficiently recovering gold and silver from abandoned gold and silver smelting graphite crucible according to claim 1, characterized in that: The spiral chute in step (2) is a single-head chute with a cross-sectional width of 25 to 30 cm, a lateral inclination of 9 to 12°, 5 to 8 blades, a feed rate of 200 to 300 kg / h, and a feed concentration of 15% to 25%. The interception valve adjusts the interception range according to the distribution of the concentrate and middling ore zones.

4. The method for efficiently recovering gold and silver from abandoned gold and silver smelting graphite crucible according to claim 1, characterized in that: The shaking table in step (3) is a two-stage fine sand shaking table with a screen surface of 60 to 88 slots, a transverse slope of 1.5 to 3.5°, a longitudinal slope of 0.5 to 1.5°, a feed rate of 100 to 200 kg / h, a feed concentration of 25% to 35%, and a flushing water rate of 15 to 35 L / min; wherein the first-stage shaking table has a stroke of 12 to 15 mm and a stroke of 250 to 280 times / min, and the second-stage shaking table has a stroke of 8 to 12 mm and a stroke of 300 to 340 times / min.

5. The method for efficiently recovering gold and silver from abandoned gold and silver smelting graphite crucible according to claim 1, characterized in that: In step (4), potassium nitrate is added according to 2% to 5% of the weight of the gold-rich slag and mixed evenly, and the mixture is spread to a thickness of 0.5 to 2.0 cm. The mixture is then roasted for 3 to 6 hours in a muffle furnace with an operating temperature of 600 to 900° C. and a furnace door opened 2 to 5 cm.

6. The method for efficiently recovering gold and silver from abandoned gold and silver smelting graphite crucible according to claim 1, characterized in that: In step (5), the ash residue is mixed with a sodium hydroxide solution having a concentration of 2 to 5 mol / L at a liquid-to-solid ratio of 4:1 to 6:1, and potassium nitrate in an amount of 1.0% to 2.5% by weight of the ash residue is added as a catalyst. The mixture is introduced into an autoclave to control the total pressure in the reactor to 2.0 to 5.0 MPa, the oxygen partial pressure to 0.1 to 0.5 MPa, the reaction temperature to 140 to 180° C., and the reaction time to 1 to 2.5 h. The mixture is cooled, filtered, and washed to obtain the alkaline leached residue.

7. The method for efficiently recovering gold and silver from abandoned gold and silver smelting graphite crucibles according to claim 1, characterized in that: In step (6), the alkali leaching residue is mixed with dilute hydrochloric acid having a molar mass of 3 to 5 mol / L at a liquid-to-solid ratio of 2:1 to 5:1, the temperature is controlled at 50 to 70° C., the stirring speed is 200 to 300 r / min, the reaction time is 1 to 2 h, and the crude gold powder or the crude silver powder is obtained by suction filtration and washing.

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