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