After fluorite is extracted through mineral processing, the tailings are usually discharged and stored in a tailings pond. In fact, fluorite tailings still have great utilization value. For example, the quartz in them can be further extracted. Quartz is widely used in metallurgy, building materials, electronics and other industries, especially high-purity quartz, which has higher utilization value in coatings, optics, and precision materials. Therefore, the significance of extracting quartz from fluorite tailings is not only to obtain surplus value, but also to avoid waste of resources and make the best use of them. So, let's discuss the operation method of extracting quartz from fluorite tailings.
In addition to quartz, fluorite tailings usually contain iron, sulfur, fluorine, mica and other substances. Without desludging the fluorite tailings, these substances can be removed by magnetic separation-reverse flotation to improve the purity of quartz. The specific operation steps are as follows:
(1) Magnetic separation for iron removal. The field strength is 0.15T. This step can effectively remove iron-containing minerals such as magnetite in the tailings.
(2) Reverse flotation for desulfurization. The amount of flotation agent Dingxan is 50g/t, and the amount of No. 2 oil is 2g/t. Under the condition of pH=8.0, reverse flotation is used to remove sulfur from the tailings.
(3) Reverse flotation for defluorination. The amount of modified castor oil is 100g/t, and the amount of water glass is 250g/t. Under the condition of pH=8.0, reverse flotation is used to remove fluorine.
(4) One roughing and two sweeping sequences return to reverse flotation for mica removal. Using 50g/t of modified etheramine, mica minerals were removed at pH=2.0.
Through the above four steps, iron, sulfur, fluorine, mica and other substances in the fluorite tailings were removed respectively, and a high-purity quartz concentrate with a SiO₂ grade of 98.66% and a recovery rate of 66.07% was obtained.
The pre-demuding method has certain advantages. The demuding pulp improves the foam environment. After 15.44% of the ore mud was removed in advance from a fluorite tailing, magnetic separation and flotation treatment were carried out. The grade of quartz concentrate has reached 99.11% and the recovery rate is 58.16%. Although the recovery rate is not high, the grade of quartz is higher than that of quartz concentrate without demuding treatment, which improves the application value.
In addition, pre-demuding can also reduce the interference of other impurities in fluorite tailings on subsequent flotation and purification processes, avoid the investment of some equipment and process costs, and improve the quality of quartz concentrate while saving costs.
To extract quartz from fluorite tailings, it is necessary to go through grinding, flotation, crystal extraction, particle size classification and other steps. The specific process flow is as follows:
1. Grinding: crush and screen the fluorite tailings to remove impurities and particles that do not meet the requirements. Use a crusher to crush the quartz fluorite ore to obtain crushed stone, and screen the crushed stone through a conveying and screening device; the crushed fluorite tailings are ground and graded.
2. Flotation: The crushed stone obtained by screening and with a particle size that meets the requirements is conveyed to the first flotation device. The pH in the first flotation device is 8-9.5; the temperature in the first flotation device is controlled at 30-40℃. After the fluorite is floated by the first flotation device, the quartz-containing ore is obtained and enters the second flotation device for quartz floatation.
3. Extracting crystals: In the quartz extraction device, the quartz particles containing impurities are dissolved through the reaction tank, and then the quartz crystals are precipitated. The quartz crystals are separated from the solution and extracted by a separator.
4. Particle size classification: The dried quartz particles are subjected to particle size classification, and the quartz particles are classified according to different particle size ranges using a screening device.
The common equipment for extracting quartz from fluorite tailings mainly includes crushing and screening equipment, grinding and classification equipment, flotation equipment, magnetic separation equipment, etc.
The crusher is used to crush the ore of quartz-type fluorite ore to obtain gravel.
The conveying and screening device includes two conveying shafts, a conveyor belt and a block. There are several sieve holes on the conveyor belt, and the sieve holes are of the same size and are evenly arranged, with an aperture of less than 5mm. It is used to screen gravel of different sizes, and the gravel that meets the requirements is collected and enters the next link.
The ball mill further grinds the ore into fine particles.
The classifier classifies the ground ore, and the unqualified particle size is returned to the ball mill for further grinding, and the qualified products enter the next step of magnetic separation or flotation.
The flotation equipment is divided into the first flotation equipment and the second flotation equipment. The first flotation equipment is used to float the fluorite in the quartz-type fluorite ore to obtain the quartz-containing ore. The second flotation equipment is used to float the quartz in the quartz-containing ore to obtain the ore with a high quartz content.
Magnetic separation equipment is mainly used for iron removal from fluorite tailings, including magnetic drums, high gradient magnetic separators, etc. Quartz and iron minerals are separated by magnetic differences.
The quartz extraction device includes a reaction tank and a separator.
The reaction tank is divided into a first reaction tank and a second reaction tank. The first reaction tank is used to dissolve the quartz particles containing impurities, and the second reaction tank is used to precipitate quartz crystals.
The separator includes a first separator and a second separator. The first separator is used to separate impurities in the quartz slurry after dissolution in the first reaction tank, and the second separator is used to separate and extract the quartz crystals precipitated in the second reaction tank from the solution.
Extracting quartz from fluorite tailings can not only obtain quartz to create economic benefits, but also has important significance for reducing the stockpile volume of tailings and reducing resource waste. In actual production, the fluorite tailings should first be subjected to mineral processing tests to determine the content of quartz in the tailings, select a suitable extraction process, and weigh the cost input and output ratio to ensure economic benefits before operating.
