A method for improving gold recovery from a floated gold concentrate

Abstract

The application is a method for improving the gold recovery rate of the gold concentrate, which comprises the steps of grinding classification, pre-leaching flotation and cyanide gold extraction. The gold-bearing pyrite is mostly concentrated in the high-sulfur gold concentrate, and most of the single gold is enriched in the high-grade gold concentrate, so that the fine distribution of gold minerals in the flotation product is realized. After the optimization of the flotation process, the gold minerals in the low-sulfur gold concentrate are a few fine-grained single gold and gold minerals associated with gangue minerals, and the gold minerals in the high-grade gold concentrate are mostly single and rich intergrowth gold minerals, and the two kinds of gold concentrates are directly leached without grinding. The high-sulfur gold concentrate is subjected to grinding treatment. The application solves the technical problems that the gold-bearing pyrite is lost in the flotation tailings due to the fine flotation particle size in the gold concentrate smelting process, and the gold grade of the cyanide residue is high during the leaching of the flotation tailings; and solves the technical problem that the fine embedded particle size of gold and silver minerals affects the cyanide leaching of gold and silver.

Description

Technical Field

[0001] This invention relates to the process of extracting gold and silver from gold concentrate, and more particularly to a method for improving the leaching rate of gold and silver from gold-bearing sulfide ores, belonging to the field of gold mineral beneficiation and hydrometallurgy. Background Technology

[0002] Cyanide extraction is a major modern method for gold production. Since its successful experimental research in the 1960s, the gold concentrate cyanidation process has been applied in many gold mines. The main characteristics of this process are: high gold grade in the concentrate after flotation enrichment, low ore volume entering the cyanidation process, low cyanide consumption, good treatment effect of acidification on cyanide-containing wastewater, savings in basic investment, small footprint, reduced production costs, and the ability to produce gold locally. Typical cyanidation processes for flotation concentrates are mainly used for gold-bearing quartz vein sulfide ores and gold-bearing altered rock ores, which are simple gold mineral types and represent the vast majority of gold production. Gold-bearing sulfide primary ores have low mud content, are easily enriched by flotation, and have a high recovery rate.

[0003] In addition to gold and silver, which are the main recovered metals, gold concentrate from flotation also contains high levels of valuable elements such as copper, lead, zinc, and sulfur. To improve the economic efficiency of enterprises, comprehensive recovery of these valuable elements is necessary. To increase the recovery rate of multiple metals and reduce the amount of hydrogen cyanide spillage during the recovery of copper, lead, and zinc from the cyanide residue after leaching, a flotation separation process can be added before leaching to achieve effective enrichment of multiple metal elements, and cyanide leaching can be carried out in series according to the properties of the materials.

[0004] The invention patent application CN109351465A, entitled "A Method for Comprehensive Recovery of Multiple Metal Elements in Gold Concentrate through Cascade Separation," discloses the following process: Stage 1 involves pre-flotation of low-sulfur gold concentrate using a highly efficient mixed activator and flotation reagents; Stage 2 involves alkaline leaching and cyanidation for gold extraction from high-sulfur concentrate; Stage 3 involves environmentally friendly wet leaching of gold and silver from low-sulfur tailings; Stage 4 involves preferential lead-zinc beneficiation of high-sulfur gold concentrate tailings (i.e., the first low-gold, high-sulfur concentrate); Stage 5 involves copper beneficiation of lead-zinc tailings; Stage 6 involves roasting and acidification of copper tailings (i.e., the second low-gold, high-sulfur concentrate) to enrich gold, silver, and iron concentrate; and Stage 7 involves environmentally friendly wet leaching of gold and silver from iron concentrate. This patent highlights a technical method for multi-metal recovery from cyanide tailings of low-gold, high-sulfur gold concentrates. However, this process does not significantly improve the gold and silver recovery rate. The process is complex and requires roasting of the high-sulfur cyanide tailings. It is practical for large-scale gold concentrate processing plants with complete supporting facilities, but not feasible for processing plants that do not have roasting technology.

[0005] Since gold minerals mostly exist in pyrite as associated, embedded, or disseminated minerals, a fine grinding process of the gold concentrate is required before flotation to ensure sufficient liberation of individual gold minerals and guarantee gold leaching rate. However, after grinding, the unique physicochemical properties of the fine particles lead to decreased selectivity of flotation reagents, resulting in the loss of some gold-bearing pyrite in the flotation tailings. In this latter portion of the gold-bearing pyrite, some gold minerals are encapsulated by pyrite, causing a higher grade in the cyanide residue after leaching. Furthermore, with large-scale gold mining, the particle size of gold minerals is gradually becoming finer, and finer-particle-sized, difficult-to-process ores are becoming a major trend in cyanide gold beneficiation. Therefore, improving the gold leaching rate of this portion of the gold concentrate has become a pressing technical challenge for many gold cyanide smelting companies. Summary of the Invention

[0006] The technical problem to be solved by this invention is to provide a method for improving the gold recovery rate of flotation gold concentrate. First, the feed particle size and reagent system of the flotation process are optimized to solve the technical problem that the loss of gold-bearing ferrite in the flotation tailings due to the fine flotation particle size, which in turn causes the gold grade of the flotation tailings to rise during leaching. Second, the technical problem that the fine particle size of gold and silver minerals affects the recovery of gold and silver in cyanide leaching is solved.

[0007] This invention is achieved through the following technical solutions.

[0008] A method for improving the gold recovery rate of flotation gold concentrate includes the following steps:

[0009] 1) Grinding and classification: Grinding and classification of gold concentrate raw materials to obtain gold concentrate with a fineness of -38μm accounting for 60-80%;

[0010] 2) Pre-leaching flotation: After the gold concentrate in step 1) has been ground and classified, it is mixed with flotation process water and then the dispersant water glass, activator ammonium chloride, flotation collector butyl xanthate, butyl ammonium black powder and ethyl thiocyanate are added in sequence. After mixed flotation, mixed flotation concentrate and mixed flotation tailings as low sulfur gold concentrate are obtained.

[0011] The mixed flotation concentrate is mixed with flotation process water and then subjected to separate flotation; the separate flotation tailings are used as high-sulfur gold concentrate and as high-grade gold concentrate.

[0012] 3) Cyanide gold extraction: After solid-liquid separation of the low-sulfur gold concentrate obtained in step 2), the filtrate is returned to the flotation process for recycling. The solid is leached with cyanide lean liquor after slurry preparation. The sodium cyanide concentration in the cyanide leaching is 0.20-0.25%, the leaching time is 36-40 hours, and the pulp concentration is 30-35%. After leaching, the pulp is washed and separated into liquid and solid to obtain precious liquor and low-sulfur gold concentrate cyanide residue.

[0013] After solid-liquid separation of the high-sulfur gold concentrate obtained in step 2), the filtrate is returned to the flotation process for recycling. The solid is slurryed with cyanide lean liquor and then ground using an ultrafine grinding machine. After grinding, the high-sulfur gold concentrate is cyanide leached. The sodium cyanide concentration of the cyanide leaching is 0.25-0.30%, the leaching time is 40-48 hours, and the pulp concentration is 40-45%. After leaching, the pulp is washed and separated into liquid and solid components to obtain precious liquor and high-sulfur gold concentrate cyanide residue.

[0014] After solid-liquid separation of the high-grade gold concentrate obtained in step 2), the filtrate is returned to the flotation process for recycling. The solid is then subjected to cyanide leaching after being prepared with lean liquor: the first stage leaching uses sodium cyanide with a concentration of 0.80-0.90%, a leaching time of 48-54 hours, and a pulp concentration of 40-45%. After the first stage leaching, the pulp is filtered by a filter press, and the filtrate is the precious liquor. The filter cake is then prepared with lean liquor for a second stage leaching, using sodium cyanide with a concentration of 0.90-1.00%, a leaching time of 48-60 hours, and a pulp concentration of 40-45%. After the second stage leaching, the pulp is filtered by a filter press and washed, and the filtrate and washing liquid are the precious liquor. The filter cake is the high-grade gold concentrate cyanide residue.

[0015] Preferably, the high-grade gold concentrate cyanide residue obtained in step 3) is used to recover copper, lead and zinc by flotation.

[0016] Preferably, the gold concentrate raw material has a gold grade of 48-55 g / t, a silver grade of 55-60 g / t, a sulfur grade of 35-40%, and a fineness of -38 μm accounting for 40%-55%.

[0017] Preferably, in step 2), the concentration of the gold concentrate and flotation process water slurry is 27-28%; the dosages of dispersant water glass, activator ammonium chloride, flotation collector butyl xanthate, butyl ammonium black powder and ethyl thiocyanate are 900-1100 g / t, 180-220 g / t, 200-260 g / t, 220-260 g / t and 220-260 g / t, respectively.

[0018] Preferably, the mixed flotation in step 2) refers to: after grinding and classifying, the gold concentrate is subjected to reagents added sequentially in a stirred tank, and then subjected to one roughing process to obtain a roughing concentrate and tailings; the roughing concentrate is subjected to two closed-circuit cleaning processes to obtain a mixed flotation concentrate; and the roughing tailings are subjected to three closed-circuit scavenging processes to obtain a low-sulfur gold concentrate.

[0019] Preferably, the separation flotation in step 2) refers to: the mixed flotation concentrate undergoes one roughing process to obtain a roughing concentrate and tailings; the roughing concentrate undergoes two closed-circuit cleaning processes to obtain a high-grade gold concentrate; the roughing tailings undergo two closed-circuit scavenging processes to obtain a high-sulfur gold concentrate; the mixed flotation concentrate and flotation process water are mixed to form a pulp with a pulp concentration of 33-35%; flotation collectors butyl xanthate, ethyl thiocyanate, and butyl ammonium black powder, and depressant lime are added to the roughing process, with dosages of 30-50 g / t, 35-45 g / t, 35-45 g / t, and 1800-2200 g / t, respectively; flotation collectors butyl ammonium black powder and butyl xanthate are added to the scavenging process, with dosages of 15-25 g / t and 15-25 g / t, respectively.

[0020] Preferably, in step 3), the proportion of the fineness after grinding to -20μm is 85-95%.

[0021] The positive effects of this invention are:

[0022] 1) This invention optimizes the feed particle size and reagent formulation of the pre-leaching flotation process, concentrating most of the gold-bearing pyrite in the high-sulfur gold concentrate and enriching the vast majority of individual gold particles in the high-grade gold concentrate, thus achieving a refined distribution of gold minerals in the flotation product. After the flotation process optimization, the gold minerals in the low-sulfur gold concentrate consist of a few fine-grained individual gold particles and gold minerals associated with gangue minerals, while the gold minerals in the high-grade gold concentrate are mostly individual particles and rich in intergrowth gold minerals. Both types of gold concentrates have low levels of intergrowth and inclusion gold minerals, allowing for direct leaching without grinding to obtain good cyanide residue indicators. The high-sulfur gold concentrate, on the other hand, contains mostly gold minerals closely associated with pyrite, with a higher content of intergrowth and inclusion gold minerals, requiring grinding. Through these technical measures, the gold-bearing pyrite is accurately separated from individual gold particles and gold minerals associated with gangue, significantly reducing the grinding load in subsequent ultrafine grinding processes and laying the foundation for further reducing the gold grade in the leached cyanide residue.

[0023] 2) In response to the problem of gold minerals being encapsulated and finely embedded in pyrite in high-sulfur gold concentrate, this invention uses an ultrafine grinding device to grind the fine-grained gold-bearing pyrite after it has been enriched in the high-sulfur gold concentrate. This further increases the degree of liberation of individual gold minerals, and more fully exposes the gold and silver in the inclusions, thereby improving the leaching environment and reducing the grade of cyanide slag.

[0024] 3) This invention allows for the direct leaching of low-sulfur, high-grade gold concentrate that does not require grinding; it concentrates the symbiotic gold minerals that require grinding into high-sulfur gold concentrate and then grinds them uniformly, so that the grinding cost is precisely applied to the gold minerals that coexist with pyrite, promoting the efficient recovery of gold minerals in cyanidation operations. Detailed Implementation

[0025] To better understand and implement this invention, the invention will be further described below with reference to specific embodiments.

[0026] Example 1: A method for improving the gold recovery rate of flotation gold concentrate, comprising the following steps:

[0027] 1) Grinding and classification: Using gold concentrate with a gold grade of 48.13 g / t, a silver grade of 57.05 g / t, a sulfur grade of 37.15%, and a fineness of -38 μm of 44.4% as raw material, gold concentrate with a fineness of -38 μm of 60% is obtained through grinding and classification.

[0028] 2) Pre-leaching flotation: After grinding and classification in step 1), the gold concentrate is mixed with flotation process water and the pulp concentration is controlled at 27.5%. Dispersant water glass is added sequentially at a dosage of 1000 g / t, activator ammonium chloride at a dosage of 200 g / t, and flotation collectors butyl xanthate, butyl ammonium black powder, and ethyl thiocyanate at dosages of 240 g / t, 240 g / t, and 240 g / t, respectively. After mixed flotation with one roughing, three scavenging, and two cleaning processes, a low-sulfur gold concentrate with a gold grade of 2.26 g / t, a silver grade of 9.70 g / t, a sulfur grade of 4.30%, and a yield of 25.00% and a mixed flotation concentrate with a gold grade of 63.42 g / t, a silver grade of 72.83 g / t, a sulfur grade of 48.10%, and a yield of 75.00% are obtained. After mixing the flotation concentrate with flotation process water and conditioning the pulp, the pulp concentration is controlled at 33%. Following a roughing, scavenging, and cleaning separation flotation process, flotation collectors butyl xanthate, ethyl thiocyanate, and butyl ammonium black, along with depressant lime, are added to the roughing operation at dosages of 40 g / t, 40 g / t, 40 g / t, and 2000 g / t, respectively. In the scavenging operation, flotation collectors butyl ammonium black and butyl xanthate are added at dosages of 20 g / t and 20 g / t, respectively. This yields a high-sulfur gold concentrate with a gold grade of 15.03 g / t, a silver grade of 28.00 g / t, a sulfur grade of 48.46%, and a yield of 68.16%, and a high-grade gold concentrate with a gold grade of 545.62 g / t, a silver grade of 519.59 g / t, a sulfur grade of 44.51%, and a yield of 6.84%.

[0029] 3) Cyanide gold extraction: The low-sulfur gold concentrate obtained in step 2) is subjected to solid-liquid separation in a filter press. The filter press filtrate is returned to the flotation process for recycling. The filter cake is leached with cyanide lean liquor after slurry preparation. The sodium cyanide concentration is 0.20%, the leaching time is 36 hours, and the pulp concentration is 35%. After leaching, the pulp is washed and separated into liquid and solid components to obtain precious liquor and cyanide residue from the low-sulfur gold concentrate.

[0030] The high-sulfur gold concentrate obtained in step 2) is subjected to solid-liquid separation by a filter press. The filter press filtrate is returned to the flotation process for recycling. The filter cake is slurryed with cyanide lean liquor and then ground using an ultrafine grinding machine. After grinding, the fineness of -20μm accounts for 88.4%. After grinding, the high-sulfur gold concentrate is cyanide leached with a sodium cyanide concentration of 0.25% for 44 hours and a pulp concentration of 40%. After leaching, the pulp is washed and separated into liquid and solid components to obtain precious liquor and high-sulfur gold concentrate cyanide residue.

[0031] The high-grade gold concentrate obtained in step 2) is subjected to solid-liquid separation using a filter press. The filter press filtrate is returned to the flotation process for recycling. The filter cake is then subjected to cyanide leaching after being prepared with lean liquor. The leaching process employs a "two-leaching, two-washing" process. In the first stage of leaching, the sodium cyanide concentration is 0.80%, the leaching time is 48 hours, and the pulp concentration is 40%. After the first stage of leaching, the pulp is subjected to solid-liquid separation again using a filter press. The filter press filtrate is the precious liquor. The filter cake is then subjected to a second stage of leaching after being prepared with lean liquor. The leaching time is 48 hours, the pulp concentration is 40%, and the sodium cyanide concentration is 0.90%. After leaching, the pulp is filtered and washed again using a filter press. The filtrate and washing liquid are the precious liquor, and the filter cake is the high-grade gold concentrate cyanide residue. The cyanide residue is then used for flotation to recover copper, lead, and zinc.

[0032] After cyanide leaching, the gold grade of the cyanide leaching residue from low-sulfur gold concentrate was 0.30 g / t; the gold grade of the cyanide leaching residue from high-sulfur gold concentrate was 0.98 g / t; and the gold grade of the cyanide leaching residue from high-copper gold concentrate was 1.95 g / t. The weighted average of the three types of cyanide leaching residue yielded a comprehensive gold grade of 0.88 g / t, with a gold leaching rate of 98.18%.

[0033] Example 2, a method for improving the gold recovery rate of flotation gold concentrate, comprising the following steps:

[0034] 1) Grinding and classification: Using gold concentrate with a gold grade of 50.57 g / t, a silver grade of 58.44 g / t, a sulfur grade of 38.44%, and a fineness of -38 μm of 46.0% as raw material, gold concentrate with a fineness of -38 μm of 65% is obtained through grinding and classification.

[0035] 2) Pre-leaching flotation: After grinding and classification in step 1), the gold concentrate is mixed with flotation process water and the pulp concentration is controlled at 27.7%. Dispersant water glass is added in sequence at a dosage of 1050 g / t, activator ammonium chloride at a dosage of 210 g / t, and flotation collectors butyl xanthate, butyl ammonium black powder, and ethyl thiocyanate at dosages of 250 g / t, 245 g / t, and 250 g / t, respectively. After mixed flotation with one roughing, three scavenging, and two cleaning processes, a low-sulfur gold concentrate with a gold grade of 2.34 g / t, a silver grade of 10.20 g / t, a sulfur grade of 3.90%, and a yield of 21.33% and a mixed flotation concentrate with a gold grade of 63.65 g / t, a silver grade of 71.52 g / t, a sulfur grade of 47.80%, and a yield of 78.67% are obtained. After mixing the flotation concentrate with flotation process water and conditioning the pulp, the pulp concentration is controlled at 34%. Following a roughing, scavenging, and cleaning separation flotation process, flotation collectors butyl xanthate, ethyl thiocyanate, and butyl ammonium black, along with depressant lime, are added to the roughing operation at dosages of 45 g / t, 42 g / t, 44 g / t, and 2100 g / t, respectively. In the scavenging operation, flotation collectors butyl ammonium black and butyl xanthate are added at dosages of 22 g / t and 21 g / t, respectively. This yields a high-sulfur gold concentrate with a gold grade of 12.44 g / t, a silver grade of 26.40 g / t, a sulfur grade of 48.50%, and a yield of 71.66%, and a high-grade gold concentrate with a gold grade of 587.11 g / t, a silver grade of 532.75 g / t, a sulfur grade of 40.70%, and a yield of 7.01%.

[0036] 3) Cyanide gold extraction: The low-sulfur gold concentrate obtained in step 2) is subjected to solid-liquid separation in a filter press. The filter press filtrate is returned to the flotation process for recycling. The filter cake is leached with cyanide lean liquor after slurry preparation. The leaching sodium cyanide concentration is 0.22%, the leaching time is 38 hours, and the pulp concentration is 34%. After leaching, the pulp is washed and separated into liquid and solid components to obtain precious liquor and low-sulfur gold concentrate cyanide residue.

[0037] The high-sulfur gold concentrate obtained in step 2) is subjected to solid-liquid separation by a filter press. The filter press filtrate is returned to the flotation process for recycling. The filter cake is slurryed with cyanide lean liquor and then ground using an ultrafine grinding machine. After grinding, the fineness of -20μm accounts for 92.0%. After grinding, the high-sulfur gold concentrate is cyanide leached with a sodium cyanide concentration of 0.28% for 46 hours and a pulp concentration of 42%. After leaching, the pulp is washed and separated into liquid and solid components to obtain precious liquor and high-sulfur gold concentrate cyanide residue.

[0038] The high-grade gold concentrate obtained in step 2) is subjected to solid-liquid separation using a filter press. The filter press filtrate is returned to the flotation process for recycling. The filter cake is then subjected to cyanide leaching after being prepared with lean liquor. The leaching process employs a "two-leaching, two-washing" process. In the first stage of leaching, the sodium cyanide concentration is 0.85%, the leaching time is 50 hours, and the pulp concentration is 42%. After the first stage of leaching, the pulp is subjected to solid-liquid separation again using a filter press. The filter press filtrate is the precious liquor. The filter cake is then subjected to a second stage of leaching after being prepared with lean liquor. The leaching time is 54 hours, the pulp concentration is 42%, and the sodium cyanide concentration is 0.95%. After leaching, the pulp is filtered and washed again using a filter press. The filtrate and washing liquid are the precious liquor, and the filter cake is the high-grade gold concentrate cyanide residue. The cyanide residue is then used for flotation to recover copper, lead, and zinc.

[0039] After cyanide leaching, the gold grade of the cyanide leaching residue from low-sulfur gold concentrate was 0.28 g / t; the gold grade of the cyanide leaching residue from high-sulfur gold concentrate was 0.88 g / t; and the gold grade of the cyanide leaching residue from high-copper gold concentrate was 1.94 g / t. The weighted average of the three types of cyanide leaching residue yielded a comprehensive gold grade of 0.83 g / t, with a gold leaching rate of 98.37%.

[0040] Example 3, a method for improving the gold recovery rate of flotation gold concentrate, comprising the following steps:

[0041] 1) Grinding and classification: Using gold concentrate with a gold grade of 52.50 g / t, a silver grade of 59.42 g / t, a sulfur grade of 38.80%, and a fineness of -38 μm of 47.2% as raw material, gold concentrate with a fineness of -38 μm of 73% was obtained through grinding and classification.

[0042] 2) Pre-leaching flotation: After grinding and classification in step 1), the gold concentrate is mixed with flotation process water and the pulp concentration is controlled at 28.0%. Dispersant water glass is added in sequence at a dosage of 1100 g / t, activator ammonium chloride at a dosage of 220 g / t, and flotation collectors butyl xanthate, butyl ammonium black powder, and ethyl thiocyanate at dosages of 260 g / t, 255 g / t, and 260 g / t, respectively. After mixed flotation with one roughing, three scavenging, and two cleaning processes, a low-sulfur gold concentrate with a gold grade of 2.14 g / t, a silver grade of 8.80 g / t, a sulfur grade of 3.14%, and a yield of 20.46% and a mixed flotation concentrate with a gold grade of 65.45 g / t, a silver grade of 72.44 g / t, a sulfur grade of 47.97%, and a yield of 79.54% are obtained. After mixing the flotation concentrate with flotation process water and adjusting the pulp, the pulp concentration is controlled at 35%. Following a roughing, scavenging, and cleaning separation flotation process, flotation collectors butyl xanthate, ethyl thiocyanate, and butyl ammonium black, along with depressant lime, are added to the roughing operation at dosages of 50 g / t, 45 g / t, 45 g / t, and 2200 g / t, respectively. In the scavenging operation, flotation collectors butyl ammonium black and butyl xanthate are added at dosages of 24 g / t and 23 g / t, respectively. This yields a high-sulfur gold concentrate with a gold grade of 11.79 g / t, a silver grade of 25.80 g / t, a sulfur grade of 48.80%, and a yield of 71.88%, and a high-grade gold concentrate with a gold grade of 569.03 g / t, a silver grade of 510.11 g / t, a sulfur grade of 40.21%, and a yield of 7.66%.

[0043] 3) Cyanide gold extraction: The low-sulfur gold concentrate obtained in step 2) is subjected to solid-liquid separation in a filter press. The filter press filtrate is returned to the flotation process for recycling. The filter cake is leached with cyanide lean liquor after slurry preparation. The sodium cyanide concentration is 0.25%, the leaching time is 40 hours, and the pulp concentration is 35%. After leaching, the pulp is washed and separated into liquid and solid components to obtain precious liquor and cyanide residue from the low-sulfur gold concentrate.

[0044] The high-sulfur gold concentrate obtained in step 2) is subjected to solid-liquid separation by a filter press. The filter press filtrate is returned to the flotation process for recycling. The filter cake is slurryed with cyanide lean liquor and then ground using an ultrafine grinding machine. After grinding, the fineness of -20μm accounts for 95.0%. After grinding, the high-sulfur gold concentrate is cyanide leached with a sodium cyanide concentration of 0.30% for 48 hours and a pulp concentration of 44%. After leaching, the pulp is washed and separated into liquid and solid components to obtain precious liquor and high-sulfur gold concentrate cyanide residue.

[0045] The high-grade gold concentrate obtained in step 2) is subjected to solid-liquid separation using a filter press. The filter press filtrate is returned to the flotation process for recycling. The filter cake is then subjected to cyanide leaching after being prepared with lean liquor. The leaching process employs a "two-leaching, two-washing" process. In the first stage of leaching, the sodium cyanide concentration is 0.90%, the leaching time is 54 hours, and the pulp concentration is 43%. After the first stage of leaching, the pulp is subjected to solid-liquid separation again using a filter press. The filter press filtrate is the precious liquor. The filter cake is then subjected to a second stage of leaching after being prepared with lean liquor. The leaching time is 56 hours, the pulp concentration is 45%, and the sodium cyanide concentration is 1.00%. After leaching, the pulp is filtered and washed again using a filter press. The filtrate and washing liquid are the precious liquor, and the filter cake is the high-grade gold concentrate cyanide residue. The cyanide residue is then used for flotation to recover copper, lead, and zinc.

[0046] After cyanide leaching, the gold grade of the cyanide leaching residue from low-sulfur gold concentrate was 0.25 g / t; the gold grade of the cyanide leaching residue from high-sulfur gold concentrate was 0.80 g / t; and the gold grade of the cyanide leaching residue from high-copper gold concentrate was 1.90 g / t. The weighted average of the three types of cyanide leaching residue yielded a comprehensive gold grade of 0.77 g / t, with a gold leaching rate of 98.53%.

[0047] After optimization of the flotation process, all the above embodiments, based on process mineralogical analysis, show that the gold minerals in low-sulfur gold concentrate are a few fine-grained individual golds and gold minerals associated with gangue minerals, while the gold minerals in high-grade gold concentrate are mostly individual golds and rich intergrowth gold minerals. The content of poor intergrowth and inclusion gold minerals in these two types of gold concentrates is relatively small, and good cyanide residue indicators can be obtained by direct leaching without grinding.

Claims

1. A method for improving the gold recovery rate of flotation gold concentrate, characterized in that... Includes the following steps: 1) Grinding and classification: Grinding and classification of gold concentrate raw materials to obtain gold concentrate with a fineness of -38μm accounting for 60-80%; 2) Pre-leaching flotation: After the gold concentrate in step 1) has been ground and classified, it is mixed with flotation process water and then the dispersant water glass, activator ammonium chloride, flotation collector butyl xanthate, butyl ammonium black powder and ethyl thiocyanate are added in sequence. After mixed flotation, mixed flotation concentrate and mixed flotation tailings as low sulfur gold concentrate are obtained. The mixed flotation concentrate is mixed with flotation process water and then subjected to separate flotation; the separate flotation tailings are used as high-sulfur gold concentrate and as high-grade gold concentrate. 3) Cyanide gold extraction: After solid-liquid separation of the low-sulfur gold concentrate obtained in step 2), the filtrate is returned to the flotation process for recycling. The solid is leached with cyanide lean liquor after slurry preparation. The sodium cyanide concentration in the cyanide leaching is 0.20-0.25%, the leaching time is 36-40 hours, and the pulp concentration is 30-35%. After leaching, the pulp is washed and separated into liquid and solid to obtain precious liquor and low-sulfur gold concentrate cyanide residue. After solid-liquid separation of the high-sulfur gold concentrate obtained in step 2), the filtrate is returned to the flotation process for recycling. The solid is slurryed with cyanide lean liquor and then ground using an ultrafine grinding machine. After grinding, the high-sulfur gold concentrate is cyanide leached. The sodium cyanide concentration of the cyanide leaching is 0.25-0.30%, the leaching time is 40-48 hours, and the pulp concentration is 40-45%. After leaching, the pulp is washed and separated into liquid and solid components to obtain precious liquor and high-sulfur gold concentrate cyanide residue. After solid-liquid separation of the high-grade gold concentrate obtained in step 2), the filtrate is returned to the flotation process for recycling. The solid is then subjected to cyanide leaching after being prepared with lean liquor: the first stage leaching uses sodium cyanide with a concentration of 0.80-0.90%, a leaching time of 48-54 hours, and a pulp concentration of 40-45%. After the first stage leaching, the pulp is filtered by a filter press, and the filtrate is the precious liquor. The filter cake is then prepared with lean liquor for a second stage leaching, using sodium cyanide with a concentration of 0.90-1.00%, a leaching time of 48-60 hours, and a pulp concentration of 40-45%. After the second stage leaching, the pulp is filtered by a filter press and washed, and the filtrate and washing liquid are the precious liquor. The filter cake is the high-grade gold concentrate cyanide residue. In step 2), the concentration of the gold concentrate and flotation process water is 27-28%; the dosages of dispersant water glass, activator ammonium chloride, flotation collector butyl xanthate, butyl ammonium black powder, and ethyl thiocyanate are 900-1100 g / t, 180-220 g / t, 200-260 g / t, 220-260 g / t, and 220-260 g / t, respectively. In step 3), the proportion of ore with a fineness of -20μm after grinding is 85-95%.

2. The method for improving gold recovery rate in flotation gold concentrate as described in claim 1, characterized in that: The high-grade gold concentrate cyanide residue obtained in step 3) is used to recover copper, lead and zinc through flotation.

3. The method for improving gold recovery rate in flotation gold concentrate as described in claim 1, characterized in that: The gold concentrate raw material has a gold grade of 48-55 g / t, a silver grade of 55-60 g / t, a sulfur grade of 35-40%, and a fineness of -38 μm accounting for 40-55%.

4. The method for improving the gold recovery rate of flotation gold concentrate as described in claim 1, characterized in that... The mixed flotation mentioned in step 2) refers to: after grinding and classifying, the gold concentrate is subjected to reagents added sequentially in a stirred tank, and then undergoes one roughing process to obtain a roughing concentrate and tailings; the roughing concentrate undergoes two closed-circuit cleaning processes to obtain a mixed flotation concentrate; and the roughing tailings undergo three closed-circuit scavenging processes to obtain a low-sulfur gold concentrate.

5. The method for improving gold recovery rate in flotation gold concentrate as described in claim 1, characterized in that... The separation flotation described in step 2) refers to: the mixed flotation concentrate undergoes one roughing process to obtain a roughing concentrate and tailings; the roughing concentrate undergoes two closed-circuit cleaning processes to obtain a high-grade gold concentrate; the roughing tailings undergo two closed-circuit scavenging processes to obtain a high-sulfur gold concentrate; the mixed flotation concentrate and flotation process water are mixed to form a pulp with a pulp concentration of 33-35%; flotation collectors butyl xanthate, ethyl thiocyanate, and butyl ammonium black powder, and depressant lime are added to the roughing process at dosages of 30-50 g / t, 35-45 g / t, 35-45 g / t, and 1800-2200 g / t, respectively; flotation collectors butyl ammonium black powder and butyl xanthate are added to the scavenging process at dosages of 15-25 g / t and 15-25 g / t, respectively.