Gold ore flotation process

The theoretical basis of various gold flotation processes is roughly the same, that is, gold ore particles can aggregate at the liquid-gas or water-oil interface due to the hydrophobic properties of their own surfaces or the hydrophobic properties obtained by flotation reagents.

The most widely used method is froth flotation. The ore is crushed and pulverized to dissociate various minerals into individual particles, and make the particle size meet the requirements of the flotation process. Various flotation agents are added to the milled pulp and mixed and mixed to interact with the mineral particles to expand the floatability difference between different mineral particles. The adjusted gold ore pulp is sent to the flotation cell, stirred and aerated.

The ore particles in the slurry contact and collide with the air bubbles, and the ore particles with good floatability selectively adhere to the air bubbles and are carried up to form a mineralized foam layer composed of gas-liquid-solid three-phase. The pulp surface overflows, and then dewaters and dries into a gold concentrate product. Mineral particles such as gangue that cannot float are discharged from the bottom of the flotation tank with the pulp as tailings.

The process is used to reflect the principle scheme of various ore sorting, including the process used for sorting, the sequence between each process, etc. Due to the large differences in the characteristics of gold mines such as khenbu particle size, dissemination characteristics, argillization characteristics, and associated mineral components, there are certain differences in the flotation process of different gold mines. The common principle processes are as follows:

1. Flotation + cyanide leaching

It is often used to treat sulfide ore containing a certain amount of gold and silver. In the process flow, the gold ore is firstly subjected to flotation operation, and a small amount of concentrate obtained by flotation is then subjected to cyanidation leaching. Compared with all-slime cyanidation, this process does not require fine grinding and leaching of all minerals, which is more time-saving, labor-saving and money-saving.

2. Flotation + concentrate roasting + calcine leaching

This gold ore flotation process is generally used for insoluble gold-arsenic ore, gold-antimony ore and gold-pyrite with extremely high sulfide content. A small amount of concentrate is obtained by flotation, which reduces the processing capacity of subsequent operations. The purpose of intermediate roasting is to remove elements such as arsenic and antimony that are harmful to cyanidation leaching.

3. Flotation + flotation concentrate pyroprocessing

A small amount of concentrate products should be obtained by flotation first, and then the remaining impurities should be removed by heating, melting and smelting. This gold ore flotation process is often used to treat most sulfide ores containing gold and silver. During the flotation process, gold and silver enter the closely related minerals such as copper and lead, and finally the flotation concentrate is sent to the smelter for purification.

4. Flotation + flotation tailings or medium ore cyanation + flotation concentrate roasting cyanidation in situ

This method is commonly used in the industry to process quartz sulfide ore containing gold telluride, pyrrhotite, chalcopyrite and other sulfide ores. The sulfide ore concentrate is obtained by flotation, and the gold and silver in it are exposed by roasting. Cyanide leaching was performed on the roasted product. At the same time, due to the high content of gold and silver in the middle and tailings obtained by flotation, it needs to be recovered by cyanidation leaching.

5. Raw ore cyanide + cyanide tailings flotation

For some sulfide ore containing gold and silver, cyanidation cannot completely recover the gold and silver in it, so the cyanided slag is flotated to improve the gold and silver recovery rate.

Gold ore flotation process is a relatively complex beneficiation process. In the beneficiation process, there are many types of flotation processes, such as preferential flotation, mixed flotation, partial mixed preferential flotation, equal flotation, branched series flotation, flash flotation, and rapid flotation.

Russia-Ukraine conflict brings uncertainty to global nickel supply

 Market research firm Fitch Solutions Country Risk and Industry Research (Fitch Solutions) said in its July 8 "Global Nickel Outlook" report: The Russia-Ukraine conflict has created uncertainty about the global supply of mined nickel - especially High-grade nickel used as battery-grade nickel in the electric vehicle (EV) industry.

Last year, Russian miner Norilsk Nickel alone provided about 17% of the world's primary nickel supply. Overall, Russia accounts for about 21% of global primary nickel production, followed by Canada with 17%, Australia with 14% and China with 10%.

While nickel is the fifth most common element on Earth and is currently mined in more than 25 countries, high-grade sulfide deposits located in mature mining areas are mostly depleted and require new and riskier jurisdictions Do additional exploration.

However, apart from the uncertainty surrounding Russia, high refined nickel prices and less disruption from the Covid-19 outbreak could lead to strong growth in nickel mine production this year and next, Fitch Solutions said.

The most important driver of this growth will be a recovery in production in Indonesia and the Philippines, where the Covid-19 outbreak has severely mining activity in 2020 and 2021.

Output in Indonesia was hit particularly hard last year, Fitch Solutions said, as a record number of Covid-19 cases led to the country's reimposition of lockdown restrictions. Fitch Solutions forecasts that global nickel production will grow at an average annual rate of 3.1% through 2026, before accelerating to an average of 5% by 2031.

Still, Fitch Solutions said both growth rates would be below the 6.6% year-on-year average achieved between 2010 and 2019, driven by higher nickel prices at the time and strong growth in Indonesian production. Fitch Solutions also said it expects annual global nickel production to reach 3.65 million tonnes by 2031, up from 2.46 million tonnes in 2021.

"As battery-grade primary nickel undergoes significant demand growth brought about by the green transition, the main supply risk and obstacle for battery makers is adequate primary supply," Fitch Solutions said.

Meanwhile, the company says the main potential "game changer" is the successful conversion of secondary nickel (low-quality nickel with a nickel content below 99.8%) to primary nickel.

However, the process, while promising, remains technically and environmentally challenging, which Fitch Solutions said points to tighter supplies of battery-grade nickel over the next two to three years - at a time when EV sales are expected to flourish. On the other hand, the supply of non-battery-grade nickel will remain ample.

Fitch Solutions said Australia and Indonesia would remain the world's largest suppliers of nickel. However, Australia will overtake Indonesia with its endowment of high-grade primary sulphide ore, while Indonesia plans to catch up by trying to convert its secondary nickel ore to primary.

The company also highlighted significant high-grade nickel opportunities in Canada, with substantial high-quality sulphide ore resources. Canadian Nickel also enjoys a better sustainability record and lower emissions than its competitors.

Overall, Fitch Solutions said high nickel prices and blocked nickel ore flows from Russia will drive investment in nickel ore from other markets, including Indonesia, the Philippines and Australia. This will lead to strong growth in nickel ore production this year and next, especially in Indonesia and the Philippines.

However, the company said the most vulnerable part of the global nickel ore supply pipeline - outside Russia - is in Indonesia, and any delay in the development of downstream nickel processing facilities could lead to the grounding of the country's nickel ore, reducing incentives for miners to boost output .

In addition, Indonesia will need to overcome technical challenges to cost-effectively convert an ample supply of secondary nickel ore into battery-grade primary nickel.

The complete method of copper oxide flotation

 Copper oxide is a black oxide of copper. In nature, copper is a typical sulphurophile element, mainly in the form of copper sulfide, but copper oxide minerals will be formed under strong oxidizing conditions.

Copper oxide is insoluble in water and/alcohol, soluble in acid, ammonium chloride and potassium cyanide solution, slow to dissolve in ammonia solution, can react with strong alkali, copper oxide is widely used in dry manufacture of ceramics, enamel, glaze, desulfurizer etc., can also be used to make oxygen, catalysts and green glass.

In the beneficiation process, most copper oxides need to be sulfided by chemicals, and then beneficiate. Compared with dry copper sulfide, the selection is more complicated and more chemicals are used. The beneficiation process of copper oxide (including oxygen-sulfur mixed copper ore) can be divided into two categories: flotation method and chemical beneficiation method. Below we mainly describe these two types of beneficiation processes.

• Copper oxide flotation method

Flotation is one of the commonly used beneficiation processes for copper oxide ore. According to the different properties of copper oxide ore, there are sulfide flotation, fatty acid flotation, amine flotation, and emulsion.

Flotation method and sting mixture-neutral oil flotation method, etc.

1. Vulcanization flotation method

Sulfation flotation method is divided into conventional sulfidation flotation and hydrothermal sulfidation flotation.

Conventional sulfidation flotation: This method is to first sulfide copper oxide minerals (using sodium sulfide or other vulcanizing agents), and then use good xanthate collectors to conduct flotation operations. The lower the value, the faster the vulcanization operation, and the more easily vulcanized with vulcanizing agents such as sodium sulfide.

The copper oxide minerals treated by the sulfide flotation method are mainly copper carbonates, such as malachite, azurite and other minerals, or cuprite, but the dry silica malachite needs special treatment first, otherwise the sulfurization effect Not good, not even vulcanized.

Note: When oxidizing copper minerals, it is recommended to add vulcanizing agents step by step, so that ammonium sulfate and aluminum sulfate can help the vulcanization of oxidized minerals.

Hydrothermal sulfidation flotation: This method extends the conventional sulfidation flotation method, which is to carry out the sulfidation operation under hot pressing conditions, so that sulfur chemically reacts with copper oxide under hot pressing conditions.

In order to obtain stable and easy-to-select man-made copper sulfide minerals, the same minerals are recovered by flotation of copper sulfide in warm water.

This method strengthens the pre-treatment of ore - the process of pre-vulcanization, but this process has high requirements on temperature, large fuel consumption and long vulcanization time.

2. Fatty acid flotation method

Fatty acid flotation, also known as direct flotation, mainly uses fatty acids and their soaps as collectors. During flotation, gangue inhibitor water glass, phosphate and slurry conditioner sodium carbonate are usually added.

Fatty acid and soap collectors can flotate malachite and azurite well, and use fatty acids with different hydrocarbon chains to flotate malachite. As long as the hydrocarbon chain is long enough, its collecting ability is very strong.

The fatty acid flotation method mostly uses dry gangue which is not a carbonate copper oxide mineral. If the gangue contains a large amount of iron, manganese and other minerals, its indicators will deteriorate, and the mesh sludge will also cause the fatty acid to fail.

3. Amine flotation method

This method mainly uses amines as collectors for flotation, which can not only be used for the separation of copper oxide, but also a common beneficiation method for copper oxide, lead and zinc minerals. Chlorothalmine, etc.

Amine type collectors are selective in choosing copper oxide, because amines also have a collection effect on many gangues. Before sorting, pre-desliming is required, but for argillaceous copper oxide, pre-desliming will lead to copper Therefore, the premise of choosing amine flotation method is to find an effective inhibitor of gangue first.

At present, gangue inhibitors include seaweed powder, xylinate (or cellulose xylosulfonate) and polyacrylic acid.

4. Emulsion flotation method

The flotation method is mainly to vulcanize copper oxide minerals first, then add copper complexing agents to form a stable lipophilic mineral surface, and then use neutral oil emulsion to cover the mineral surface.

surface, resulting in a highly hydrophobic floatable state, so that minerals can be firmly attached to the bubbles to complete the selection.

Emulsion flotation includes three aspects:

First, it is necessary to use selective organic copper complexing agent compounds, such as benzotriazole toluoyl triazole, mercaptobenzothiazole, diphenylguanidine, etc.;

One is to re-add non-polar oil emulsion to improve the adhesion between minerals and air bubbles. Non-polar oil emulsifiers include gasoline, kerosene and some oils, etc.

Third, selective inhibitors such as acrylic polymers and sodium silicate are required.

5. Chelating agent-neutral oil flotation method

This method refers to the use of a certain chelating agent and a neutral oil to form a collector to complete the flotation. It is mostly used for difficult-to-select copper oxides (such as silica malachite), which not only has high selectivity and collection effect, but also can It can ensure a high sorting index while reducing the consumption of chemicals, and the chelating agent also has a selective inhibitory effect.

However, the cost of the chelating agent is relatively high. At present, the chelating agents used include the basic dye malachite green substituted by octyl, potassium octyl hydroxamate, benzotriazole and neutral oil emulsifier, N-substituted iminodiethyl , acid salts, polyamines and condensates of organic halides, etc.

• Chemical beneficiation method

Chemical beneficiation methods are commonly used in dry refractory separation of copper oxide and mixed copper minerals with oxidation and sulfide. The use of chemical beneficiation method-combined process of copper oxide ore process can obtain good indicators, and it has many advantages such as simple process flow, low investment, low energy consumption, light pollution and low production cost.

The above are some common beneficiation methods for copper oxide minerals. For the selection of copper oxide minerals, it is necessary to determine the mineral composition and degree of difficulty of copper oxide minerals. It is recommended to find professional miners to conduct beneficiation tests, and customize the report according to the actual situation. In order to effectively select useful minerals from other places, remember not to apply them indiscriminately.

Ball mill: summer cooling method

The main bearing of the ball mill is one of the important components of the ball mill, which has an important influence on the operation efficiency of the ball mill.

Under the high temperature in summer, the main bearing of the ball mill is prone to high temperature of the bearing pad, and even a bearing accident in severe cases. In this article, we will discuss how to solve the problem of the high temperature of the bearing pad of the main bearing of the ball mill.

1. Replace the ball mill lubricating oil in time

During the operation of the ball mill, heat is generated due to the relative rotational friction between the hollow shaft and the bearing bush, which increases the temperature of the main bearing. Therefore, the friction can be reduced by replacing the lubricating oil, so that a uniform oil film can be formed on the bearing surface. Avoid increasing the temperature of the main bearing.

2. Adjust the cooling water and cooling device of the ball mill

The cooling of the ball mill is very important. The cooling water in the main bearing bush and the water in the main bearing oil tank cooler are the two main waters for the main bearing of the ball mill. The temperature of the cooling water has a great influence on the temperature of the main bearing of the ball mill, and the temperature of the cooling water is low. The cooling effect of the lubricating oil is fast and the cooling effect is good. Increasing the cooling water flow will also reduce the temperature of the main bearing bush.

3. Improve the environmental conditions of the ball mill

The temperature of the ball mill itself is greatly affected by the surrounding environment. In summer, the ambient temperature is high, and the temperature of the bearing bush of the ball mill is also high. The doors and windows of the factory building, the doors and windows of the oil pump room and the observation hole of the large tile should be opened to improve the ventilation conditions of the environment where the ball mill is located and reduce the temperature of the lubricating oil.

In addition, if conditions permit, an axial flow fan can be installed in the oil pump station to increase the circulating flow of air and reduce the temperature of the lubricating oil. The temperature can also be reduced by adding spray water to the oil return pipe and the oil outlet pipe.

4. Increase the cooling area of the oil pump

The cooler in the ball mill oil pump can be re-selected, or the cooling area of the ball mill lubricating oil can be increased by connecting the cooler in series, the heat exchange effect of the ball mill lubricating oil can be improved, and the temperature of the lubricating oil fed into the ball mill can be reduced. reduce bearing temperature

Below are the parameters of some of our ball mills for your reference

Development of the roller center rotating device of the rake thickener

 The rake thickener is the main concentration equipment of the beneficiation plant and an important link in the beneficiation system; it is used for the purpose of clarifying the muddy water after washing, and is used as circulating water for washing, and at the same time, it can recover the ore settlement. Therefore, the rake thickener is the key equipment to maintain the normal production of the washing plant. When the rake thickener fails, a part of the washing mud water cannot be clarified. For example, if this part of the washing water is recycled, the washing water concentration will gradually increase, and the washing production will be interrupted within a few hours.

The mud settling equipment originally used in the washing plant is a rake thickener with a peripheral drive caster type. The central column transmission bearing of the thickener often has the ball being squeezed away, which increases the running resistance of the rake frame and causes the production of beneficiation. Interruption; when dealing with faults and replacing the bearings, you need to drain the water in the rake thickener pool, and then lift the upper cage.

The structure of the original rake thickener center column transmission device is that a special pressure bearing is arranged between the upper rotating frame and the lower fixed frame. This kind of bearing structure is circular, the rolling ball is installed on the cage and placed between the upper and lower bearing rings, and the lower bearing ring is installed on the fixed bracket. The upper rotating bracket is fixedly connected with the rake frame and can be placed on the center column, and the rake thickener rotates along the center column. Because of this structure, the pressure bearing is in a relatively humid environment during long-term operation, and it is inconvenient to inject oil. It is also subject to the weight of the rake frame, the steady flow cylinder and the settled mud for a long time, but it is corroded and worn out. It can reduce the strength of the cage and increase the gap with the ball after wear. Long-term operation will cause serious deformation of the bearing cage. After being squeezed by the balls and the upper and lower frames, the bearing cage will also be broken. After the bearing cage is deformed and fractured, the movement gap between the upper and lower frames of the ball is increased, and the remaining body of the bearing cage causes the balls to squeeze each other, which will eventually cause the balls to be squeezed. After the bearing is damaged, the center transmission can only rely on the interactive friction between the upper and lower shaft rings. The increased friction and the squeeze between the balls increase the resistance distance of the rake frame. In this case, the rake thickener The applicable mud sedimentation thickness is reduced. When the mud volume in the pool is increased, long-term operation will cause the rake to be crushed or the motor to burn, which will interrupt production.

From the perspective of central transmission, the pressure bearing structure between the upper and lower frames of the original design frequently fails during actual production. The main problem is that the pressure bearing structure is not suitable for the transmission under the special working conditions of the rake thickener. Therefore, the original pressure bearing structure is transformed into a roller transmission.

According to the analysis of the effect: after the transformation is completed, because an oil injection pipe is connected to each roller oil injection hole, the oil can be injected on the rake platform, which is convenient for maintenance, low wear during operation, and low failure rate, making the maintenance cycle longer; After the replacement of the roller drive, the friction of the center column transmission is greatly reduced, and the running resistance moment of the rake frame is reduced, so that the thickness of the sedimentation mud adapted to the rake thickener is increased compared with the original bearing structure; You can observe the running status of the wheel on the top, so as to find all kinds of faults. When replacing the rollers, there is no need to drain the water from the rake thickener, nor to lift the upper cage, and the replacement can be completed on the cage.

After the center column bearing structure of the rake thickener was transformed into a roller structure, after several years of operation, the effect was good, and there was no failure. It not only increased the capacity of the mud water treatment system, but also reduced the impact of production, but also contributed to other mineral processing. The transformation of the rake thickener in the factory provides an effective attempt.

Reformation of Feeding Device of Deep Cone Thickener

Modern tailings water systems generally use closed loops. Thickeners are the key equipment of the tailings water treatment system. The concentration effect of the thickeners will directly affect the operation of the entire concentrator. The structure of the original feeding device mainly includes The defoaming barrel, the feed pipe, the upper straight section of the stabilizing barrel, the upper cone section of the stabilizing barrel, the middle straight section of the stabilizing barrel, the sieve plate and the lower cone section of the hidden barrel are composed of; The overflow weir of the thickener.

The structure of the defoaming cylinder is too simple, the mixing effect of the slurry and flocculant in the defoaming cylinder is poor, and the settling effect of the flocculant is poor; the straight section between the defoaming cylinder and the stabilizing barrel will be connected by a feed pipe, and the slurry will enter the stabilizer. The feed kinetic energy of the straight section between the barrels is large, which affects the sedimentation effect of the thickener, and the concentration efficiency is low; the upper end of the straight section on the stabilizer barrel is higher than the thickener overflow weir, and the clarified water at the upper part of the thickener cannot enter the original feed Inside the device, the flocs have not undergone the process of dilution, and the sedimentation speed of the flocs has slowed down.

The static flow stabilizer is composed of an inlet pipe, a cylinder, a baffle plate, a uniform cloth and a plate outlet pipe. After the flocculant is mixed with the slurry, the direction of the fluid is changed through the baffle plate and the uniform plate to make the flocculant and the slurry full The mixing of the kinetic energy of the mineral pulp at the same time can improve the flocculation effect.

The static steady flow mixer is equipped with two discharge pipes, which can further reduce the kinetic energy of the slurry.

The spiral material stabilization device is composed of an overflow cylinder, a cylinder, a spiral blade, a cloth plate, an inner cone and a lower cone; the upper end of the overflow cylinder is lower than the overflow weir of the thickener, and there are countless numbers on the upper part of the overflow cylinder A "rectangular" slot; the clarified water on the upper part of the thickener will flow through the upper end of the overflow cylinder and the "rectangular" slot into the spiral stabilizer, which realizes the self-dilution of the slurry, and the flocs are diluted to speed up the continuation The settlement rate.

The spiral blades on the inner wall of the spiral material stabilization device are distributed with multiple slots; the slurry entering the cylinder along the spiral blades gradually rises by its own kinetic energy, and a part of the slurry continues to rise along the spiral blades; The slurry flowing to the next spiral blade at the slot and the next spiral blade collides and mineralizes; the remaining part of the slurry flows to the center of the middle cylinder, and further collides and mineralizes with the falling slurry, making the flocculant and the slurry Fully mix to improve the flocculation effect.

Because the concentration of the slurry inside the spiral stabilizer is higher than the slurry injected onto the cone, part of the slurry passes through the small holes on the cone and collides with the spirally rising slurry in countercurrent; while reducing the kinetic energy of the slurry, it further improves Concentrated effect.

After the improvement, it has been running very well so far; the use of static steady flow mixer has improved the flocculant settlement effect of the flocculant; the kinetic energy of the slurry input is reduced through two-person feed pipes, and the purpose of mutual dilution is achieved; through the spiral The spiral blade in the material stabilization device consumes the kinetic energy of the slurry; the upper end of the spiral material stabilization device is lower than the overflow weir of the thickener, which realizes the self-dilution of the slurry and accelerates the sedimentation speed of the slurry; the final concentration of the overflow water of the thickener is small to ensure In order to improve the quality of the circulating water in the system, Xining and its consumption will be saved, reducing operating costs. After the transformation, it can be widely used in large-scale concentrators, and can replace ordinary rake thickeners to process mine tailings slurry.

Innovative microbubble flotation of flotation machine

 The dual-flow microbubble flotation method is a compressed air flotation method that realizes the pulping process and the separation process. The unique microbubble mineralizer and slurry release head design of the trough-type dual-flow flotation machine increases the precipitation of bubbles. The surface area increases the contact area between the concentrate and the microbubbles, and the mineralization efficiency is correspondingly improved. In the flotation process of the trough-type dual-flow microbubble flotation machine, the coal slurry will be pumped out of the mixing tank by a pump and then pumped into the slurry distribution header of the trough-type microbubble flotation machine, and then distributed evenly to multiple groups of minerals The mineralization unit of the carburetor passes through the mineralizer, the inverted U-shaped mineralization tube, and finally is sprayed out of the tube by the nozzle. The air will be pressed into the mineralization unit under a certain pressure, and a large number of tiny bubbles will be formed through the microporous tube in the mineralizer. The bubbles and coal slurry complete the mineralization process in the mineralization tube, and finally sprayed to In the sorting tank, at this time, the pressure drops sharply, and a large number of bubbles merged into the coal slurry are formed and precipitated quickly. The coal particles float up to the surface of the flotation tank, overflow naturally along the periphery and enter the clean coal collection tank. A small amount of fine bubbles and A large amount of intermediate density materials enter the medium coal tank, and the tailings will enter the tailings tank through the U-shaped tube, which plays a role in adjusting the liquid level.

It adopts a multi-tank structure similar to the traditional mechanical agitation flotation machine. The upper part of the tank body is a rectangular connected structure, and there is an overflow tank on the periphery to discharge the clean coal. A rectangular diversion tank is opened on the overflow to increase the overflow. The perimeter is convenient to allow the clean coal to flow out smoothly. There are multiple pyramids of the same size in the lower part of the tank, and the lower part of each pyramid has an underflow outlet and a circulation outlet.

In order to further reduce the total height of the flotation machine body, so as to facilitate the disassembly, inspection and maintenance of the flotation machine related accessories, the mineralized coal slurry will enter the inverted U-shaped mineralization tube at a high speed and be in a state of high turbulence in the tube. Continuously fold back and collide for secondary mineralization, and eventually it will be ejected from the lower end release head.

The complete flotation process of the trough-type dual-flow microbubble flotation machine is a set of two flotation processes with main washing. The underflow of the main washing tank body enters the rewashing buffer barrel, and is pumped into the rewashing tank body. The overflow of the main washing flotation body is used as the final clean coal. The main washing buffer barrel is arranged in the rewashing material buffer barrel, and the rewashing buffer barrel and the rewashing tank body are integratedly arranged, which saves space to the greatest extent.

On the basis of the integration of the previous flotation machine, the trough type dual-flow microbubble flotation machine further increases the processing capacity of the flotation machine, reduces the height of the flotation machine body, and optimizes the entire process. It is a dual-flow microbubble flotation machine. A breakthrough in the serialization of the separator product will further enhance the technical advantages and market competitiveness of the dual-fluid microbubble flotation machine.

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