【Technology】Gold mining process

 1. Mining

Mining is the extraction of economically valuable minerals or other substances from the ground, and all mining sites are mineral-rich deposits. Mining techniques are basically divided into two forms: open pit mining and underground mining. After exploration and feasibility studies are completed, ore is mined from the surface or underground using machinery such as excavators, drills, explosives and trucks.

2. Crushing mining process

The ore mined is very large. At present, the maximum ore particle size of open pit mines is 1000mm1500mm, and the maximum ore particle size of underground mines is 300mm600mm. Due to the close symbiosis of useful minerals and gangue minerals, such large ores cannot be directly separated. To separate them from each other, the ore must be crushed to a certain particle size before the next beneficiation operation.

3. Transportation during mining

Typically, belt conveyors are used to feed bulk ore to primary and secondary crushers, and then feed the crushed ore to vibrating screens to obtain different sizes.

4. Screening of the mining process

The screening process also plays a different role in the gold mining process.

Pre-screening: Before the ore enters a certain stage of the crusher, pre-screening the qualified products that meet the requirements. This process not only prevents the ore from being over-crushed, increases the productivity of the crusher, but also prevents the crusher from clogging.

Inspection and screening: After crushing, screening should be carried out to check the particle size of the crushed products, so that the unqualified extra-large ore particles can be sent back to the crushing operation to be crushed again.

5. Grinding during mining

Crushing is a continuation of the crushing process. Its purpose is to separate most of the useful mineral particles in the ore into monomers and classify them so that the particle size meets the requirements of the classification operation. In general, we support the principle of grinding more and grinding less to save costs.

6. Classification of mining processes

Classification: In the medium, substances are divided into different particle sizes according to different sedimentation rates.

The purpose of classification and screening is to separate the ore particles into different particle sizes, but their working principle and the particle size characteristics of the product are different.

The sieving should be strictly separated according to the sieving size;

Distinguish and classify materials according to the different settling velocities of materials in the medium.

In the grinding process, the qualified materials are usually separated in time by the method of classification, so as to avoid the excessive grinding of the ore and improve the grinding efficiency. Commonly used equipment are spiral classifiers and cyclones.

7. Gold mining process

The gold mining process mainly includes the following methods: cyanidation, flotation, gravity separation and mercury amalgamation.

8. Water treatment during mining

Coarse dewatering is relatively easy. Usually natural drainage is used, that is, natural drainage is drained by the gravity of the water itself. Dewatering of fines typically involves three operations: concentration, filtration and drying. Reclaimed water can be used for some parts of mineral processing operations, or it can be discharged after being treated to standards through a water treatment plant. 

9. Dry stacking of tailings

Concentrating hydrocyclone + high-efficiency deep cone thickener + high-efficiency multi-frequency dewatering screen, so that the final concentration can reach more than 85%, so as to achieve dry accumulation. The tailings are then used for paving, construction, etc.

【Phosphate ore flotation】Phosphate ore beneficiation and flotation reagents

Phosphorus is an important raw material for the production of phosphate fertilizer, yellow phosphorus, phosphoric acid, phosphide and other phosphate products, and is a non-renewable and alternative resource. The reserves of phosphate rock resources in my country are relatively large, but more than 70% of them are low-grade and lean ore, which cannot be industrialized only by the scrubbing process. At present, medium and low-grade phosphate rock resources are mainly used for enrichment, and the flotation effect of phosphate rock depends on the interaction between mineral particles and air bubbles in the water medium, among which flotation reagents are particularly important.

Commonly used flotation processes for phosphate ore beneficiation are: positive flotation, reverse flotation, first positive then reverse flotation, first reverse then positive flotation and double reverse flotation.

1. Positive flotation process of phosphate rock

The process is to grind the phosphate rock until the monomer is dissociated, add water to the slurry to adjust the concentration to a certain concentration, use a specific collector to enrich the useful phosphorus minerals in the foam product, and use a specific agent to inhibit the silicon in the phosphate rock. gangue minerals such as salts and carbonates. Commonly used flotation agents are "S", "L", "sulfonated phenol tar", "F" series of inhibitors.

The process is suitable for siliceous or calcium-siliceous phosphate rock, endogenous apatite, and sedimentary phosphate rock. The technological process is simple, the impurity removal effect is good, and the content of impurities such as Me and Fe can be effectively reduced. But the energy consumption is high and the beneficiation cost is high.

2. Phosphate rock reverse flotation process

In this process, inorganic acid is generally used to adjust the pH of the pulp to a certain range (pH=4.0 to 5.0), and a specific collector is used in a weakly acidic medium to enrich the dolomite into the foam product, and the phosphorus minerals remain in the tank. Commonly used flotation reagents are mainly inorganic acid regulators, modified fatty acid collectors, sulfate modification of fatty acids, or addition of auxiliary agents during their saponification process to improve their water solubility, temperature resistance, collection performance and Optional.

This process is generally suitable for the separation of phosphorus minerals and dolomite gangue minerals, and the exclusion rate of dolomite gangue minerals can reach 70% to 80%. The process does not require heating, and can be carried out at low temperature and normal temperature, which reduces energy consumption and saves costs.

3. Phosphate ore first positive and then reverse flotation process

The process is to first use inorganic alkali to adjust the pulp to weak alkalinity, use a specific collector to enrich the useful phosphorus minerals in the foam product, and leave the silicate gangue minerals in the tank to remove, and the foam is positive flotation. Concentrate, then add inorganic acid to adjust the pulp to weak acidity, positive flotation concentrate (regrinding or non-grinding), and then use collector to enrich carbonate impurities, and leave useful phosphorus minerals in the tank to obtain Reverse flotation concentrate, the main purpose of reverse flotation is to remove MgO impurities in phosphate concentrate. Commonly used are inorganic bases and inorganic acid modifiers, XM-10, water glass and sulfur-phosphorus mixed acid inhibitors.

This process is suitable for the treatment of siliceous phosphate ore, and the grade of phosphate concentrate obtained is higher than that of single positive or reverse flotation, and the combination of positive and negative can effectively improve the processing performance of phosphate concentrate, but the cost of reagents is high, which is not suitable for concentrators. The recycling of water resources has caused great difficulties.

4. Phosphate ore reverse first and then positive flotation process

In this process, the carbonate gangue is first floated with a collector in an acidic medium to obtain an anti-floating concentrate, and then the second-stage grinding is performed until the siliceous gangue is decomposed, and the phosphate rock is floated in an alkaline medium. material to obtain positive floating concentrate.

This process is suitable for low-grade silicon-calcareous collophanites. The process does not require heating and has low energy consumption, but the circulating water needs to be treated separately, which has a great impact on production.

5. Double reverse flotation process of phosphate rock

In this process, inorganic acid is generally used to adjust the pulp to weak acidity, and a part of dolomite gangue is enriched by fatty acid collectors, and then quartz minerals are enriched by fatty amine collectors. Phosphorus minerals in the tank are the final concentrate. Commonly used flotation reagents are inorganic acid modifiers, fatty acid and fatty amine collectors.

This process is mainly suitable for the treatment of mixed phosphate rock with low content of siliceous gangue and carbonate. Especially for the separation of dolomite and quartz-like gangue minerals. It can realize low and normal temperature flotation, with simple process, low energy consumption, simple pharmaceutical system and few types of pharmaceuticals. However, the amine collectors used in this process are cationic collectors, which will produce viscous foam, poor selectivity, and are more sensitive to ore slime. This makes the process more complicated.

List of quartz sand beneficiation equipment

 At present, the common quartz ore beneficiation process is to remove the mineral impurities in the quartz ore by scrubbing, magnetic separation, chute gravity separation, flotation, pickling or a combination of several methods to obtain the particle size and impurities of the quartz ore. The content meets the requirements of high-purity quartz ore. In this process, the commonly used quartz mineral processing equipment mainly includes rod mill, magnetic separator, flotation machine, hindered settler, XCIII hydrocyclone, high-frequency and high-efficiency dewatering screen, inclined plate concentrator, washing tower, desliming Buckets, slurry pumps, etc.

In this article, we will mainly introduce rod mills, magnetic separators, flotation machines, hindered settlers and XCIII hydrocyclones.

01 Rod Mill

In the processing of quartz ore, rod mills are mostly used as grinding equipment, which has good grinding effect, controllable discharge particle size and certain scrubbing function.

◆ Quartz ore grinding discharge particle size is generally between 40-120 mesh. The steel rod of the rod mill is in contact with the material surface, and it is not easy to over-grind. At the same time, it is guaranteed to grind qualified products and exclude unqualified products.

◆ Use rod mill to process quartz ore, which can scrub to a certain extent and help to remove some impurities.

◆ The steel rods and steel rods of the quartz ore rod mill have a certain screening effect on the quartz ore during the movement, so that the large particles can be lifted to the top position of each layer and concentrated to the place with strong crushing force. crushing ability.

02 Magnetic separator

Magnetic separation is one of the effective methods to remove iron-containing impurities in quartz ore, so as to remove weak magnetic impurity minerals such as hematite, limonite, and biotite including conjoined particles as much as possible.

Intensive magnetic separation usually adopts wet strong magnetic separator or high gradient magnetic separator. Generally speaking, for quartz whose impurities are mainly weak magnetic impurity minerals such as limonite, hematite, biotite, etc., it can be selected by a wet high-magnetic machine above 10000GS; for impurities mainly containing magnetite, for strong magnetic minerals, It is best to use a weak magnetic machine or a medium magnetic machine for sorting. In order to further remove a small amount of other weak magnetic minerals (such as amphibole, pyroxene, the combination of magnetic minerals and quartz), a high-gradient magnetic separator with a magnetic field strength greater than 12,000 Gauss can be used for secondary magnetic separation.

03 Flotation machine

Flotation is also a beneficiation method widely used in quartz ore processing plants, mainly to remove non-magnetic associated impurities such as feldspar and mica in quartz sand. The quartz sand beneficiation equipment used in this process is various suction mechanical stirring flotation machines (SF type flotation machine, BF type flotation machine, JJF type flotation machine) and air-filled mechanical stirring flotation machine (KYF type flotation machine). machine, XCF flotation machine)).

04 Obstructed settler

The hindered settler is a disturbance settling equipment, which is mainly composed of a cylinder, a bracket, a feed port, an overflow tank, a retaining ring, a support seat, a pressure detector, an electric valve and an automatic control system. . Special equipment especially effective for non-metals such as ores. The material is affected by the rising water flow in the cylinder to achieve the purpose of particle size classification and specific gravity separation, with high production efficiency and low energy consumption. It can be equipped with an automatic control system, and the adjustment of operating parameters is simple, convenient and easy to control. The water tank at the bottom of the cylinder can be equipped with a special rubber nozzle device. When the water stops, the rising water hole automatically closes,

In the quartz ore dressing plant, the hindered settler can strictly classify the coarse and fine particles, completely replacing the fine screen for particle size control.

05 XCⅢ Hydrocyclone

The XCIII hydrocyclone has a specially designed fish tail device in the grit chamber and a specially designed siphon device on the top of the overflow tank, so it has excellent characteristics that other hydrocyclones cannot match. Through the adjustment of the siphon device, a higher underflow concentration and a lower overflow concentration can be obtained. For the silica (quartz) industry, the overflow can be adjusted to almost release water and the underflow concentration can be as high as 85%. In addition, the specially designed fish tail device can keep the discharge concentration and overflow fineness of the swirl cone bottom flow constant when the ore feeding amount, ore feeding concentration and ore feeding pressure fluctuate within a certain range.

06 Summary

In the actual beneficiation process, the selection of quartz ore beneficiation technology and equipment is often determined according to various factors such as the nature of the quartz ore, the conditions of the beneficiation plant, and the investment budget. We need to comprehensively consider factors such as the actual situation and investment of the concentrator to determine the beneficiation plan, and customize the quartz ore beneficiation equipment to achieve an ideal return on investment.

Selection of spodumene flotation reagents

At present, the beneficiation methods of spodumene mainly include: manual separation, thermal disintegration, magnetic separation, resuspension method, flotation method and combined beneficiation method. Among them, the flotation method of spodumene is the most studied in the laboratory and the most widely used mineral processing method in industry.

1. Cationic collectors

The cationic collectors used in the flotation of spodumene ore are mainly amine collectors, which flotate gangue minerals such as quartz, feldspar and mica under acidic conditions, and leave the spodumene at the bottom of the tank. This method is often used in the roughing of spodumene, and cannot directly obtain spodumene concentrate with higher purity, and needs to be used in conjunction with other sorting methods.

In production practice, Yan Gengsheng used the process of flotation of spodumene with mixed soap and diesel oil under alkaline conditions after flotation of mica with phylloylamine under acidic conditions for a certain pegmatite spodumene ore. Mica concentrate and spodumene concentrate were obtained, and good economic benefits were obtained. In terms of single minerals, Yin Wanzhong and Sun Chuanyao studied the flotation of spodumene with the cationic collector dodecylamine without adding any activator and inhibitor, and obtained the result that the spodumene in the dodecylamine system The stone has better buoyancy conclusions.

2. Anionic collectors

The traditional spodumene anion collectors are mainly fatty acids and their soaps, namely oleic acid, oxidized paraffin soap, naphthenic acid soap, tar oil and sodium oleate, etc., alkyl sulfates and sulfonates, etc. However, due to the difference in ore properties, the increasingly complex ore composition and the comprehensive utilization of low-grade spodumene ore, the use of collectors has developed from a single drug to a mixed drug.

    Ren Wenbin used oximic acid to replace the original oxidized paraffin soap as a collector for the recyclability of spodumene tailings in Cocoto Sea, and the grade of spodumene concentrate was increased from 2.3% to 5.8%.

In terms of mixed drug use, in response to the problem of low recovery rate of high-grade spodumene of a granite pegmatite type in Jiangxi, Zhao Yun used oxidized paraffin soap and tall oil as a collector to obtain better indicators and solved the problem. The problem of low recovery rate.

Sun Wei and Ye Qiang used oxidized paraffin soap and naphthenic acid soap as collectors to conduct a flotation test on pegmatite-type spodumene (Li2O grade 1.42%) in a certain place in Sichuan, and finally obtained a concentrate with a Li2O grade of 6.04. %, a good indicator of the recovery rate of 85.88%. Liu Ningjiang conducted a flotation experiment on V26 and V38 spodumene of rare ore bodies in Keketuohai, Xinjiang, using strong stirring and scrubbing to remove sludge, and using cationic collectors and foaming agents to flotate mica under neutral and weak alkaline conditions. , and then mixed with sodium carbonate and sodium hydroxide to adjust the size, so that the pH value is 10.5 to 11.5, and the flotation process of using oxidized paraffin soap and naphthenic acid soap as collectors, obtained 5.65% to 6.37% of the flotation process. Spodumene concentrate, a good indicator of recovery of 80.77%.

3. New collectors

    In the research of spodumene collector selectivity, Wang Yuhua used a new type of chelating collector to replace the traditional oxidized paraffin soap, and realized the flotation separation of spodumene from quartz and feldspar, which not only can significantly reduce the cost of chemicals, And can greatly improve the separation between spodumene and quartz and feldspar, thereby improving the spodumene beneficiation index. At the same time, for the spodumene (Li2O grade 0.46%) and beryl in a granite pegmatite mineral, using the chelating collector YZB-17 can improve the grade and recovery rate of the mixed concentrate of spodumene and beryl. , and can realize the separation of spodumene and beryl.

    In the research on the collection performance of spodumene collector, Wang Yuhua studied sodium oleate, C7-9 hydroxamic acid, sodium dodecyl sulfonate and a new amphoteric collector YOA- The collection performance of 15 pairs of spodumene, the research results show that: the new amphoteric collector YOA-15 has a higher ability to collect spodumene than that of sodium oleate, C7-9 carboxyxamic acid and sodium dodecylsulfonate. Strong collecting ability. For the No. 3 vein spodumene ore and tailings in the tailings pond, the Cocoto Sea Concentration Plant used the new amphoteric collector YOA-15 to carry out flotation tests under different water quality, all of which showed strong collection capacity. With the foaming ability, a rough concentration of Li2O grade of 5.62% and a recovery rate of 83.3% can be achieved in one roughing.

    According to the research of many scholars, it is not difficult to find that there is less research on the reverse flotation process of spodumene, which may be related to the low content and grade of spodumene in the raw ore; in the positive flotation of anionic collectors, the traditional single It is difficult to meet the flotation separation of spodumene by the spodumene, and the combination drug is a new development direction; in terms of new collectors, it mainly focuses on multi-group chelating collectors and amphoteric collectors, but it is necessary to realize industrial production, there is still a long way to go.