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CN-121976054-A - Heap leaching method for low-grade gold ore

CN121976054ACN 121976054 ACN121976054 ACN 121976054ACN-121976054-A

Abstract

The invention relates to a heap leaching method of low-grade gold ore, which comprises the steps of crushing and classifying the ore into four particle fractions of coarse, medium, fine and fine mud, respectively adding a compound additive containing ferrous sulfate, potassium citrate, citric acid and sodium citrate into the fine particle fraction and the fine mud to carry out granulation so as to realize iron preactivation and potassium source presetting, adopting three layers of reverse gradient construction with coarse particle fraction as a bottom layer, medium particle fraction and partial granulation particles as a middle layer and residual granulation particles as an upper layer, establishing a potassium ferricyanide circulation system with concentrated spraying on the upper layer, medium layer targeting fluid replacement and aeration regeneration on the bottom layer, and utilizing Fe 2+ preactivated on the upper layer to generate partial potassium ferricyanide selective oxidation poison sand in situ. The invention utilizes the self iron source of ore, the ferrous sulfate is low-price to supplement iron, and combines the cyclic regeneration of potassium ferricyanide, thereby greatly reducing the consumption and cost of the medicament, realizing the harm reduction of arsenic, and having the advantages of high gold leaching rate, short leaching period, environmental protection, low comprehensive cost and the like.

Inventors

  • ZHANG WEIJIA
  • LI WENJUN
  • SHI TONG
  • WANG MENGLIN
  • ZHAO HONGMEI
  • HAN ZHIHUI

Assignees

  • 内蒙古自治区产业技术创新中心(内蒙古自治区科学技术检测实验中心)

Dates

Publication Date
20260505
Application Date
20260407

Claims (10)

  1. 1. The heap leaching method of the low-grade gold ore is characterized by comprising the following steps of: s1, ore crushing and grading, namely crushing low-grade gold-containing ore, screening and grading the crushed low-grade gold-containing ore into a coarse fraction, a medium fraction, a fine fraction and a fine mud fraction, wherein the coarse fraction is 5-10 mm, the medium fraction is 2-5 mm, the fine fraction is 0.5-2 mm, and the fine mud fraction is less than 0.5mm; S2, grading granulation and iron preactivation, namely adding a first compound auxiliary agent and a second compound auxiliary agent into the fine mud grade and the fine grain grade respectively for granulation to form fine mud particles and fine grain particles, wherein the first compound auxiliary agent and the second compound auxiliary agent both comprise sodium hexametaphosphate, sodium carboxymethyl cellulose, bentonite, ferrous sulfate, potassium citrate, citric acid and sodium citrate, the fine mud particles are 3-6 mm, and the fine grain particles are 4-8 mm; s3, constructing a pile by adopting a three-layer reverse-sequence gradient construction pile with an incremental gold content from bottom to top, wherein the bottom layer is the coarse fraction, the middle layer is a mixture of the middle fraction, part of fine particles and fine mud particles, and the upper layer is a mixture of the rest fine mud particles and fine particles; S4, initializing a potassium ferricyanide circulating system and regulating and controlling the upper concentrated-middle fluid replacement-bottom regeneration, namely adopting a circulating system of upper concentrated spraying, middle targeted fluid replacement and bottom aeration regeneration, spraying an initial leaching solution to the upper layer, utilizing preactivated Fe 2+ in fine mud particles of the upper layer to generate potassium ferricyanide with CN - in situ under the oxidation condition; S5, performing cyclone injection enhanced heap leaching and cyclic regeneration, namely performing layered regulation and control spraying on the ore heap by adopting a cyclone injection device; S6, treating the noble liquid and recycling gold; S7, washing and discharging tailings.
  2. 2. The heap leaching method of the low-grade gold ore is characterized in that in the step S2, the first compound additive comprises 60-100 g/t of sodium hexametaphosphate, 15-30 g/t of sodium carboxymethylcellulose, 80-150 g/t of bentonite, 8-20 g/t of ferrous sulfate, 10-25 g/t of citric acid, 5-15 g/t of sodium citrate, 25-60 g/t of potassium citrate, and 12-18% of granulating water to form 3-6 mm particles; The second compound auxiliary agent comprises 40-70 g/t of sodium hexametaphosphate, 10-20 g/t of sodium carboxymethylcellulose, 60-100 g/t of bentonite, 4-12 g/t of ferrous sulfate, 6-15 g/t of citric acid, 3-10 g/t of sodium citrate, 15-40 g/t of potassium citrate, and 10-15% of granulating water to form 4-8 mm particles.
  3. 3. The heap leaching method of low-grade gold ore according to claim 1, wherein in the step S2, surface activation pretreatment is performed on fine mud-grade and fine particle-grade materials before granulation, wherein the pretreatment adopts mechanical stirring or low-pressure airflow impact, the pressure of the low-pressure airflow impact is 0.1-0.3 mpa, the time is 3-5 min, or the mechanical stirring rotation speed is 200-500 rpm, and the time is 10-15 min.
  4. 4. The heap leaching method of low-grade gold ore according to claim 1, wherein in step S3, the three-layer reverse-order gradient heap is specifically: the bottom layer has a layer thickness of 0.4-0.6 m and 100% coarse fraction, forming a drainage skeleton region; The middle layer has a layer thickness of 1.2-1.8 m and comprises 40-50% of middle particle size fraction, 35-40% of fine particle and 10-25% of fine mud particle to form a main leaching zone; The upper layer has a layer thickness of 0.6-1.0 m, and comprises 50% -60% of fine mud particles, 40% -50% of fine particles, and a bulk integrated density of 1.5-1.7 g/cm 3 and an integrated permeability (2.4-3.2) multiplied by 10 -4 m/s.
  5. 5. The heap leaching method of low-grade gold ore according to claim 1, wherein in the step S4, the initial leaching solution contains 160-180 g/t of sodium cyanide, 15-25 g/t of thiomalic acid, and 80-100 g/t of potassium ferricyanide initially, and has a pH of 10.5-11.0; the middle layer targeting fluid infusion pipe network is buried at the upper part of the middle layer, and the fluid infusion components comprise 20-30 g/t of sodium cyanide, 8-12 g/t of thiomalic acid and pH value of 10.0-10.5; the bottom layer is regenerated by bottom aeration oxidation, the air-water ratio is 8:1-12:1, and the residence time is 2-3 hours.
  6. 6. The heap leaching method of low-grade gold ore according to claim 1, wherein in step S4, micro-nano bubbles are introduced into the initial leaching solution which is sprayed onto the upper layer in a concentrated manner through a micro-nano bubble generating device, the particle size of the bubbles is 10-100 μm, and the gas-liquid ratio is 1:50-1:200, so that the concentration of dissolved oxygen in the leaching solution reaches 10-15 mg/L.
  7. 7. The heap leaching method of low-grade gold ore is characterized in that in the step S5, the cyclone spraying device is arranged on the upper layer, the nozzle is an inverted cone nozzle with a built-in spiral diversion trench, the diameter of an inner opening is 3-3.5 mm, the diameter of an outer opening is 1-1.5 mm, the screw pitch is 0.7-0.9 mm, the working pressure is 0.08-0.15 MPa, the spraying intensity is 12-18L/(m 2 & h), and the spraying is performed for 4-6 min every 5-8 min.
  8. 8. The heap leaching method of low-grade gold ore according to claim 1, wherein in the step S4, the bottom layer is sprayed with low-intensity drops or intermittently, and the intensity is 6-10 l/(m 2 ·h).
  9. 9. The heap leaching method of low-grade gold ore according to claim 1, wherein the low-grade gold-containing ore is characterized in that the gold grade is 0.5-2.0 g/t, the total iron content is 4% -8%, the poison sand content is 0.8% -1.5%, the pyrite content is 0.5% -1.0%, the limonite and magnetite content is 5% -8%, the copper content is less than 0.1%, the gold is mainly 70% -85% of fissured gold and inter-grain gold, and the particle and fine particle Jin Zhanbi% are more than 75%.
  10. 10. The heap leaching method of low-grade gold ores, according to claim 1, is characterized in that the gold leaching rate achieved by the method is 88% -93%, the total consumption of sodium cyanide and potassium ferricyanide is less than 400g/t, the heap leaching period is 28-42 days, the arsenic concentration of tail liquid is less than 0.3mg/L, and the free cyanide of tail liquid is less than 0.5mg/L.

Description

Heap leaching method for low-grade gold ore Technical Field The invention belongs to the technical field of mineral processing, and particularly relates to a heap leaching method of low-grade gold ores, which is particularly suitable for high-efficiency heap leaching treatment of low-grade gold ores with high toxic sand, limonite and magnetite, and main micro-fine particles of gold granularity. Background The development and utilization of low-grade gold ore (Au is less than 1.0 g/t) has important significance for fully utilizing gold resources. However, the existing treatment process of the ore has the problems of low economy, high environmental protection pressure, low production efficiency and the like. The low-grade gold ore is characterized by high composition of toxic sand, limonite, magnetite and the like, and Jin Lidu is mainly micro-particles. For example, some low-grade ore has various metal mineral types and high toxic sand content, which is more than 0.9 percent (higher than that of general low-grade gold ore), the toxic sand has fine granularity, the toxic sand is in a self-semi-self diamond shape, the granularity is 0.05-0.15 mm, pyrite is 0.7 percent, the sum of limonite and magnetite is 7.0 percent, natural gold is closely associated with pyrite, natural gold is visible among cracks of the pyrite, the pyrite is partially changed into limonite, brown iron mineralized pyrite is formed, and the natural gold is endowed to the cracks and the particle edges of the brown iron in the type of the corrosive pyrite. However, the complex intercalation of gold-arsenopyrite-limonite results in cyanide leaching where arsenopyrite consumes large amounts of cyanide and releases arsenic, while limonite/magnetite cementation characteristics tend to cause clogging of the slime. Jin Lidu analysis shows that the total amount of the fine-grain gold (0.01 mm and 0.037 mm) and the fine-grain gold (0.01 mm and 0.037 mm) is more than 80%, and the occurrence state is mainly composed of fissure gold and inter-grain gold and is mainly distributed among mineral fissures such as pyrite, quartz grain gaps and toxic sand fissures. The nature of this fine-grained, fissure occurrence requires that the leaching system must possess a strong oxidising power to open the sulphide package and avoid gold losses due to reduced permeability of the slime plug. In the prior art, the full mud cyanide stirring leaching has the advantages of 0.074mm of grinding fineness, over-high grinding cost, poor economic feasibility, 1000g/t of sodium cyanide consumption, large medicament consumption, great specific surface area of toxic sand and pyrite after fine grinding, great cyanide consumption in side reaction, full contact of the toxic sand with cyanide liquid in a fine grinding state, difficult fixation of As (III) released by oxidation, difficult control of arsenic concentration in tail liquid and low leaching rate. Conventional crushing, such as ore crushing to 0-25mm heap leaching technology, has the defects of blocking pores of a heap, causing uneven seepage of leaching liquid to form short circuits and dead zones, poor permeability, uneven distribution of leaching liquid, and failure to effectively open toxic sand and pyrite packages to cause gold loss and low leaching rate. Other related processes in the prior art still have obvious defects that, for example, the prior art discloses a potassium ferricyanide-potassium ferrocyanide circulating system for alkaline desulfurization, cyaniding and gold leaching of sulphide ores, but the scheme mainly aims at stirring leaching, a large amount of potassium ferricyanide medicaments are required to be purchased externally, the cost is high, and the method is not aimed at heap leaching infiltration flow characteristics and cannot be directly applied to heap leaching. In summary, there is a need to develop a heap leaching method for such low-grade gold ores, which at least solves the problems that cyanide is consumed greatly, recycling is not possible, fine-grained mineral gold is high in content, but permeability and the like are uncontrollable, heap leaching and other large-scale production methods cannot be used, cost is high, as and other elements are polluted, fe and other components are difficult to effectively utilize, leaching rate is difficult to improve and the like. Disclosure of Invention The application overcomes the defects of the prior art, aiming at low-grade gold ore, wherein 0.5-2.0 g/t of Au, 0.8-1.5% of arsenopyrite, 5-8% of limonite and magnetite, gold is mainly slit gold/inter-particle gold (70-85%, the proportion mainly refers to gold existing form), and the problems need to be systematically solved. The invention provides a heap leaching method of low-grade gold ores, which realizes high-efficiency, economical and environment-friendly recovery through full-size-fraction differential granulation, potassium ferricyanide cyclic catalysis, upper concentrated spraying, middle-layer