A process and system for gold extraction by cyanidation of whole mud without pre-concentration

Abstract

This invention discloses a gold extraction process and system using whole-sludge cyanidation without pre-concentration, relating to the field of gold beneficiation and smelting technology. It solves the problems of low grinding efficiency, complex processes, difficulty in recovering coarse gold particles, and high safety risks in existing processes. The process includes raw ore crushing, primary grinding, gravity separation, hydrocyclone classification, secondary grinding-leaching, leaching-adsorption, smelting, and tailings treatment; the system includes corresponding crushing, primary grinding, gravity separation, hydrocyclone classification, secondary grinding-leaching, leaching-adsorption, smelting, and tailings treatment units. The key innovation is: gravity separation recovers coarse gold particles after primary grinding; the secondary stage uses an azin mill to achieve synergistic grinding-leaching, eliminating the pre-concentration stage; and the filtrate reagents are recycled. This invention features a simplified process, low energy consumption, high gold recovery rate, and safe and environmentally friendly operation, suitable for gold extraction from gold ores containing coarse gold particles that require fine grinding.

Description

Technical Field

[0001] This invention relates to the field of gold beneficiation technology, specifically to a gold extraction process and system using whole-sludge cyanidation without pre-concentration. Background Technology

[0002] The whole-sludge cyanidation gold extraction process is a common method for processing fine-grained disseminated gold ores. This process includes crushing, grinding, thickening, leaching, adsorption, and tailings treatment, offering advantages such as high beneficiation recovery rates. However, due to the requirement for fine ore particle size, processing costs are relatively high. Traditional processes often employ two-stage closed-circuit ball mill grinding. For ores requiring fine grinding, this results in low grinding efficiency and high energy consumption per unit area. Furthermore, the grinding product concentration is relatively low, necessitating a thickener for pre-concentration after grinding to meet the pulp concentration requirements of subsequent leaching operations. This not only increases infrastructure investment and operating costs but also prolongs the production process. For coarse gold particles in the ore, over-grinding and "coarse runoff" are prone to occur during the grinding cycle, making effective recovery difficult. Simultaneously, cyanidation leaching is typically carried out in separate leaching tanks, with dispersed reagent addition points. This not only increases the risk of personnel contact but also poses safety risks and high cyanide consumption due to the easy decomposition of cyanide. Therefore, there is an urgent need in this field for a new gold extraction process that can simplify the process, reduce costs and energy consumption, improve gold recovery rate and enhance operational safety. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a gold extraction process and system using whole-sludge cyanidation without pre-concentration. This process eliminates the pre-concentration step and achieves efficient, energy-saving, and safe gold extraction through innovative selection of core equipment and optimized combination of processes.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a whole-sludge cyanidation gold extraction process without pre-concentration, comprising the following steps:

[0005] ① Raw ore crushing: After the raw ore is crushed in three stages of coarse crushing, medium crushing and fine crushing in a closed circuit, a raw ore with a particle size of -12mm is obtained;

[0006] ② First-stage grinding: The -12mm particle size raw ore obtained in step ① is fed into a first-stage ball mill along with fresh water and lime for grinding to obtain the first-stage grinding product; wherein, the mass concentration of the first-stage grinding is 60-75%, and the amount of lime added is 1000-2000 kg / t. The lime is directly added to the first-stage ball mill and fully hydrolyzed into Ca(OH)2 to create an alkaline slurry environment for the subsequent addition of sodium cyanide reagent;

[0007] ③ Gravity separation: The grinding product obtained in step ② is fed into the gravity separation equipment to separate the gold-bearing sand containing gold particles. The remaining slurry is then fed into the subsequent classification operation. Taking advantage of the high density of gold particles and the characteristic of heavy minerals in the hydrocyclone feed being reverse-enriched in the sand, the freed coarse gold particles are recovered in advance.

[0008] ④ Hydrocyclone Classification: The remaining slurry from step ③ is pumped to a hydrocyclone for classification, resulting in overflow and underflow. The underflow is returned to the first-stage ball mill for grinding, while the overflow enters the second-stage grinding. The mass concentration of the hydrocyclone overflow is 40-45%.

[0009] ⑤ Two-stage grinding and leaching: The overflow from step ④ is fed into a two-stage slurry mill via a slurry pump for open-circuit grinding. Simultaneously, sodium cyanide is added to the slurry mill to perform synergistic grinding and leaching operations, yielding a finely ground slurry. The sodium cyanide is directly added inside the slurry mill, utilizing its open-circuit grinding characteristics to achieve a safe and efficient combination of grinding and leaching in a closed environment. The discharge concentration from the two-stage slurry mill is maintained above 40%, and the ore particle size of the finely ground slurry is >85% at -200 mesh.

[0010] ⑥ Leaching and adsorption: The finely ground slurry described in step ⑤ is fed into a stirring tank for pre-leaching, followed by carbon slurry adsorption to obtain gold-loaded carbon and tailings slurry; wherein, the leaching and adsorption slurry pH=11, the NaCN concentration is 0.8~1.5‰, the leaching and adsorption time is 15~20 hours, and the gold grade of the gold-loaded carbon is 600~1500g / t;

[0011] ⑦ Smelting: The gold-bearing sand obtained in step ③ and the gold-bearing carbon obtained in step ⑥ are sent together to the smelter to extract gold.

[0012] ⑧ Tailings treatment: The tailings slurry described in step ⑥ is filtered by a filter press to obtain filtrate and filter tailings with a water content of <15%. The filter tailings are discharged into the tailings pond after environmental protection treatment. The filtrate contains sodium cyanide reagent residue and is returned to the discharge of the first-stage ball mill for classification and slurry conditioning before the hydrocyclone, while realizing the recycling of the reagent.

[0013] A gold extraction system for whole mud cyanide without pre-concentration includes a crushing unit, a first-stage grinding unit, a gravity separation unit, a hydrocyclone classification unit, a second-stage grinding and leaching unit, a leaching and adsorption unit, a smelting unit, and a tailings treatment unit connected in sequence.

[0014] Crushing unit: A three-stage closed-circuit crushing equipment is used to crush the raw ore to a particle size of -12mm;

[0015] A grinding unit consists of a ball mill, the feed end of which is connected to the discharge end of the crushing unit, a fresh water supply device, and a lime addition device, for the purpose of mixing and grinding the raw ore with fresh water and lime.

[0016] Gravity separation unit: includes gravity separation equipment, the feed end of which is connected to the discharge end of a ball mill, used to separate gold-laden sand from the grinding products of the first stage;

[0017] Hydrocyclone classification unit: includes a hydrocyclone, the feed end of which is connected to the slurry discharge end of the gravity separation equipment, the underflow discharge end of which is connected to the feed end of a ball mill to form a closed loop, and the overflow discharge end of which is connected to a two-stage grinding and leaching unit.

[0018] The two-stage grinding and leaching unit includes an ammonia mill, the feed end of which is connected to the overflow outlet of a hydrocyclone. The ammonia mill is equipped with a sodium cyanide addition device to achieve coordinated grinding and leaching operations.

[0019] Leaching and adsorption unit: includes a stirring tank and a carbon slurry adsorption device. The feed end of the stirring tank is connected to the discharge end of the sand mill, and the discharge end of the stirring tank is connected to the carbon slurry adsorption device to realize the pre-leaching of mineral slurry and carbon slurry adsorption.

[0020] Smelting unit: Connected to the gold-bearing sand discharge end of the gravity separation equipment and the gold-bearing carbon discharge end of the carbon slurry adsorption equipment respectively, for gold extraction;

[0021] Tailings treatment unit: includes a filter press and a tailings dam. The feed end of the filter press is connected to the tailings slurry discharge end of the carbon slurry adsorption equipment. The filtrate discharge end of the filter press is connected to the discharge end of a section of the ball mill. The filter cake discharge end of the filter press is connected to the tailings dam.

[0022] Compared with existing technologies, the present invention provides a whole-sludge cyanidation gold extraction process and system without pre-concentration, which has the following beneficial effects:

[0023] 1. Streamlined process and high separation efficiency: Since the two-stage sand mill produces high-concentration slurry, the thickener in the traditional process is eliminated, which simplifies the process and reduces infrastructure investment and operating costs; at the same time, the grinding product directly enters the leaching system, with little slurry temperature loss and higher temperature further improves leaching efficiency, which is especially suitable for winter production.

[0024] 2. High overall gold recovery rate: By incorporating gravity separation after the initial grinding stage, coarse gold particles are recovered in advance, avoiding their loss during subsequent grinding cycles. The "grinding-leaching combined technology" allows gold minerals to be leached instantly upon liberation, reducing the chance of gold particle passivation, which is particularly beneficial for the recovery of fine gold particles. Using an abrasive mill results in finer product particle size and a narrower particle size distribution, effectively improving the leaching rate and metal recovery rate.

[0025] 3. Energy-saving and efficient: The fine grinding efficiency of the Aisha mill is 20-30% higher than that of the traditional ball mill, and the energy consumption per unit of ore grinding is reduced by 15-25%; using ceramic balls as grinding media reduces the cost of grinding media per unit of ore by 25-35%, which is especially suitable for gold ore that requires fine grinding.

[0026] 4. Excellent safety and environmental friendliness: Sodium cyanide is added in a closed cyanide mill, reducing the chance of contact with personnel. Furthermore, the strong reducing environment inside the mill reduces cyanide decomposition losses, making the working environment safer. Tailings are discharged dry after pressure filtration, with a moisture content of <15%, significantly reducing tailings dam pressure and the risk of dam failure. The filtrate is recycled within the workshop, achieving safe and efficient recovery of sodium cyanide while reducing wastewater discharge, making it environmentally friendly.

[0027] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it according to the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Specific embodiments of the present invention are given in detail below with reference to the accompanying drawings. Attached Figure Description

[0028] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0029] Figure 1 This is a flowchart of the gold extraction process in this invention. Detailed Implementation

[0030] The following is in conjunction with the appendix Figure 1 The principles and features of the present invention are described below. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. The invention is described more specifically in the following paragraphs by way of example with reference to the accompanying drawings. It should be noted that the drawings are in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the invention.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0032] This example is from a gold mine cyanidation beneficiation plant in Inner Mongolia. The gold grade of the raw ore being beneficiated is 2.06 g / t, and the maximum ore particle size is -500 mm.

[0033] like Figure 1 As shown, this embodiment provides a gold extraction process using whole mud cyanidation without pre-concentration, specifically including the following steps:

[0034] Raw ore crushing: After three-stage closed-circuit crushing, the raw ore particle size is -12mm, with a yield of 100%;

[0035] First-stage grinding: The grinding concentration in the first-stage ball mill is 70%, the lime addition is 1500 kg / t, and the proportion of -200 mesh in the first-stage grinding product is 5%.

[0036] Gravity separation: A shaking table gravity separation method was used to recover coarse gold-bearing sand. The gold content of the gold-bearing sand was 85 g / t, and the gold recovery rate of coarse gold was 4%.

[0037] Hydrocyclone grading: Hydrocyclone overflow concentration 42%, underflow sand is returned to the first stage ball mill;

[0038] Two-stage grinding and leaching: the discharge concentration of the sand mill is 41%, the discharge particle size of -200 mesh accounts for 95%, and the sodium cyanide addition is 1.2 kg / t (based on the raw ore).

[0039] Leaching and adsorption: Slurry pH=11, NaCN concentration 1.0‰, leaching and adsorption time 16 hours, gold grade of gold-loaded carbon 980g / t, gold grade of tailings 0.082g / t;

[0040] Smelting: Gold-bearing sand and gold-bearing carbon are sent to a smelter to extract gold;

[0041] Tailings treatment: The water content of the filter press tailings is 12%, and the filtrate is returned to the feed end of the hydrocyclone, with a reagent recycling rate of 30%.

[0042] In this embodiment, the total gold recovery rate is 95.87%, which is 3.2 percentage points higher than that of the traditional process; the unit ore processing cost is reduced by 18%, and infrastructure investment is reduced by 10%.

[0043] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Those skilled in the art can readily implement the present invention based on the accompanying drawings and the above description. However, any modifications, alterations, or variations made by those skilled in the art without departing from the scope of the present invention, utilizing the disclosed technical content, are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, or variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. A gold extraction process using whole mud cyanidation without pre-concentration, characterized in that, Includes the following steps: ① Raw ore crushing: After the raw ore is crushed in three stages of coarse crushing, medium crushing and fine crushing in a closed circuit, a raw ore with a particle size of -12mm is obtained; ② First stage grinding: The -12mm particle size raw ore obtained in step ① is fed together with fresh water and lime into a first stage ball mill for grinding to obtain the first stage grinding product; ③ Gravity separation: The grinding product obtained in step ② is fed into the gravity separation equipment to separate the gold-bearing sand containing gold particles. The remaining slurry is then fed into the subsequent classification operation. ④ Hydrocyclone classification: The remaining slurry from step ③ is pumped to the hydrocyclone for classification to obtain overflow and underflow. The underflow is returned to the first-stage ball mill for grinding, and the overflow enters the second-stage grinding. ⑤ Second-stage grinding and leaching: The overflow from step ④ is fed into a second-stage slurry mill for open-circuit grinding via a slurry pump. Sodium cyanide is added to the slurry mill to perform a combined grinding and leaching operation to obtain a finely ground slurry. ⑥ Leaching and adsorption: The finely ground slurry described in step ⑤ is fed into a stirring tank for pre-leaching, followed by carbon slurry adsorption to obtain gold-loaded carbon and tailings slurry. ⑦ Smelting: The gold-bearing sand obtained in step ③ and the gold-bearing carbon obtained in step ⑥ are sent together to the smelter to extract gold. ⑧ Tailings treatment: The tailings slurry described in step ⑥ is filtered by a filter press to obtain filtrate and filter tailings with a water content of <15%. The filter tailings are discharged into the tailings pond after environmental protection treatment. In step ⑧, the filtrate contains sodium cyanide residue, which is returned to the discharge of the first-stage ball mill for classification and slurry preparation before the hydrocyclone, while realizing the recycling of the reagent. In step ②, lime is directly added to the first-stage ball mill and fully hydrolyzed into Ca(OH)2, creating an alkaline slurry environment for the subsequent addition of sodium cyanide reagent; the mass concentration of the first-stage grinding is 60-75%, and the amount of lime added is 1000-2000 kg / t; In step ⑤, sodium cyanide is directly added to the inside of the arginine mill. By utilizing the open-circuit grinding characteristics of the arginine mill, grinding and leaching are safely and efficiently combined in a closed environment. In step ⑤, the discharge concentration of the second-stage sand mill is maintained above 40%, and the particle size of the fine-ground slurry is >85% at -200 mesh.

2. The gold extraction process by cyanidation of whole mud without pre-concentration according to claim 1, characterized in that: In step ③, the gravity separation operation utilizes the high density of gold particles and the characteristic of heavy minerals in the hydrocyclone feed being reverse-enriched in the sediment to recover the freed coarse gold particles in advance.

3. The gold extraction process by cyanidation of whole mud without pre-concentration according to claim 1, characterized in that: In step ④, the mass concentration of the hydrocyclone overflow is 40-45%.

4. The gold extraction process by cyanidation of whole mud without pre-concentration according to claim 1, characterized in that: In step ⑥, the leaching adsorption slurry pH is 11, the NaCN concentration is 0.8-1.5‰, the leaching adsorption time is 15-20 hours, and the gold grade of the gold-loaded carbon is 600-1500 g / t.

5. A gold extraction system for whole-sludge cyanidation without pre-concentration, comprising the gold extraction process for whole-sludge cyanidation without pre-concentration as described in any one of claims 1-4, characterized in that, The system comprises, in sequence, a crushing unit, a primary grinding unit, a gravity separation unit, a hydrocyclone classification unit, a secondary grinding-leaching unit, a leaching-adsorption unit, a smelting unit, and a tailings treatment unit. The crushing unit employs a three-stage closed-circuit crushing system. The primary grinding unit includes a ball mill, the feed end of which is connected to the discharge end of the crushing unit, a fresh water supply device, and a lime addition device. The gravity separation unit includes a gravity separator, the feed end of which is connected to the discharge end of the primary ball mill. The hydrocyclone classification unit includes a hydrocyclone, the feed end of which is connected to the slurry discharge end of the gravity separation device, and the underflow discharge end of the hydrocyclone is connected to the feed end of the primary ball mill. The two-stage grinding and leaching unit includes an abrasive mill, the feed end of which is connected to the overflow outlet of a hydrocyclone, and the abrasive mill is equipped with a sodium cyanide addition device; the leaching and adsorption unit includes a stirring tank and a carbon slurry adsorption device, the feed end of which is connected to the outlet of the abrasive mill, and the outlet of which is connected to the carbon slurry adsorption device; the smelting unit is connected to the gold-loaded sand outlet of the gravity separation device and the gold-loaded carbon outlet of the carbon slurry adsorption device respectively; the tailings treatment unit includes a filter press and a tailings dam, the feed end of which is connected to the tailings slurry outlet of the carbon slurry adsorption device, the filtrate outlet of which is connected to the discharge end of a first-stage ball mill, and the filter cake outlet of which is connected to the tailings dam.

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