I. Geological exploration
(1) Type of exploration and network
On the basis of the inspection of the ore deposits, the exploration type of the fluorite deposit is determined according to the spatial extension law of the ore body, the complexity of the ore body shape, the stability of the ore body and the distribution characteristics of the useful components of the ore.
Basis for the classification of fluorite deposits:
1. Large-scale ore body of ore body size: the length is generally 800m and the depth is 300-500m. Medium-sized ore body: length 300-800m, depth 100-400m. Small ore body: length less than 300m, depth 10~300m.
2. The ore body shape is relatively simple: continuous single vein ore body, layered, layered ore body. More complicated: intermittent single vein ore body, complex vein ore body, branched saddle-shaped ore body. Complex: complex vein ore bodies, beaded ore bodies, lenticular, cystic ore bodies, and ore bodies damaged by karsts.
3. The stability of the ore body is stable: the industrial ore body is continuous over a long distance, the thickness expansion and contraction changes regularly, and it fluctuates above the recoverable thickness. The thickness variation coefficient is less than 50%. It is more stable: the industrial ore body is basically continuous over a long distance, and there is a narrow section or a non-mine section. The thickness variation coefficient is 50% to 80%. Unstable: The thickness of the ore body changes sharply, and the recoverable and non-recoverable sections alternate. The thickness variation coefficient is greater than 80%.
4. The distribution of useful components of ore is uniform: the mineral composition is simple. The calcium fluoride grade change coefficient is less than 30%. More uniform: complex mineral composition. The grade change coefficient of calcium fluoride is 30% to 60%. There are stones in the ore body. Uneven: The mineral composition is complex and the content of harmful components is high. The calcium fluoride grade change coefficient is greater than 60%. There are more stones in the ore body.
According to the above geological factors that affect the difficulty of exploration, the types of exploration of fluorite deposits in China are divided as follows:
Type I exploration. There are no examples of layered ore bodies with large ore bodies, simple shapes, stable thickness, uniform grade and no structural influence.
Type II exploration. The size of the ore body is large to large. The ore body shape is a relatively simple continuous or micro-discontinued single vein ore body, which compares the regular vein-like ore bodies. The thickness is stable or stable, and the grade is uniform or uniform. No structural damage or little impact. Such as Zhejiang Yangjia, Houshu, Hunan Hengnan, Henan Chenlou and other fluorite deposits.
Type III exploration. The size of the ore body is large to large. The shape of the ore body is complex, such as complex vein ore body, lenticular ore body, saddle-shaped ore body, ore body. The thickness is relatively stable. The grade is more uniform or uneven. No structural damage or some influence. As the river in Zhejiang, Liaoning and silver mountain Sanbaotun and other fluorite deposits.
Type IV survey. The size of the ore body is small to medium. The shape of the ore body is complex, mainly for beaded single vein ore body, lenticular or cystic ore body. The thickness is unstable to be stable. The grade is more uniform to uneven, and there is no structural damage or damage. For example, Zhejiang No. 5 and No. 6 ore bodies, Sichuan Erheshui No. 1 ore body.
According to the geological exploration of mines in China and the practice of mine production, combined with the characteristics of known exploration types, the fluorite deposit exploration specifications stipulate the network degree (Table 1).
Table 1 fluorite deposit exploration engineering spacing table
(ii) Industrial indicators
From our current situation at home and abroad fluorite mineral resources of fluorite mine production, beneficiation economic and technological conditions and market conditions, we must implement the "revenue and reducing expenditure" simultaneously "development and protection" principle of attaching equal importance to cherish resources, make full use of resources. When exploring fluorite deposits, it is necessary to delineate the ore body in accordance with the above spirit. For the industrial indicators used in the geological exploration reports that provide the basis for the design of the mine construction, the geological exploration department shall put forward preliminary opinions, conduct technical and economic comparison and demonstration by the industrial department, and propose specific industrial indicators, which shall be determined by the provincial or provincial industrial authorities. . The general industrial indicators for a single fluorite deposit are shown in Table 2.
Table 2 General industrial indicators of fluorite deposits
In the exploration process of mineral deposits, comprehensive exploration and comprehensive evaluation must be carried out for other useful minerals with (co-).
Zinc sulfide, lead with respect to the (co) raw fluorite deposits, typically 5% CaF 2, to be noted that the comprehensive evaluation, so that when the main mining, fluorite may comprehensive recycling.
Second, mining
(1) Mining technical conditions
The genesis of fluorite deposits in China is mainly medium-low temperature hydrothermal filling type and sedimentary transformation type. The distribution of mineral deposits is wide, but the scale is generally small, some are several hundred meters long and a few are more than one kilometer. The depth is from 100 meters to several hundred meters, and the thickness is small, only a few meters to a dozen meters, and the individual reaches 20 to 30 meters. And the ore grade is rich and poor. The dip angle of the ore body is steep, generally 70°～80°, the surrounding rock is relatively stable, the hydrogeological conditions are relatively simple, and the mining conditions are better.
Most of the fluorite deposits are shallowly buried and can be exploited for open pit mining. Deep ore bodies are mainly mined by shafts, and a few are inclined wells. In addition to a few key mines in China, most mines have no formal design, especially small and medium-sized mines, which are produced in the form of side-by-side exploration.
(ii) Mining methods
Fluorite minerals, like other minerals, generally use both open and pit mining methods.
The shallow part of the ore body is mainly open-pit mining. Manual rock drilling with steel brazing head, manual mining and transportation of slag. A few use mechanical rock drilling and mechanical transportation. Open-pit mining has low cost, simple equipment and good economic benefits. At present, most township enterprises and mass mining employ this method.
Deep ore bodies are mainly developed by shafts, and a few are inclined wells. The mining process consists of three stages: development, acquisition and recovery.
Most of the vertical section of the shaft is divided into double grids, one grid half or three grids according to the needs of development and production. The main grid raises ore, materials and personnel, and the other is used to lift counterweights, laying plumbing, cables and ladders.
The main body and roadway development projects include: shaft, Shimen, along the vein transportation lane, prospecting and veining, ventilation, and safety exit.
Auxiliary projects include: water tanks, pump rooms, drainage ditches, sedimentation tanks, air supply, and substation chambers.
After the development work is completed, the mining work is done, and then the mining is carried out.
Mining work must adhere to the principle of “poor and rich and miningâ€, “size, thickness, and miningâ€, so as to cherish resources and make full use of resources.
There are four types of fluorite mining methods:
1. Subsection mining method. In the designed mining block, the middle section of the transportation lane will open the bottom (upper) roadway 5~6m upwards, and then erect the stratified roadway along the vein every 5~7m upwards, and the direction along each lane will be 25~30m upward. One layer digs into the patio, and finally expands the patio of the upper roadway to the transport lane into a funnel. When mining, it is terminated by one end or both ends, and it is retreated or topped. This kind of mining method has a large workload, with many gravel and broken mines. The labor intensity of the workers is high and the efficiency is low. The workers entering the goaf are not safe and picking mines, and the application is less.
2. Single bevel and double bevel filling mining method. The mining engineering and mining methods are basically the same as the section mining, and the empty areas are broken and single-sided or double-sided filling. The top plate after blasting and falling mine can be controlled, and the ground pressure of the nugget is reduced, and the recovery rate can reach more than 90%.
3. Small middle section mining method (also known as reverse mining method). The length of the mining area is generally about 60m. The roadway is still stratified by 5~8m above the bottom roadway. The distance between the cutting patios in the stratification is 15~20m, the spacing of the bottom funnel is 5~6m, and the lower part of the funnel is installed with the ore chute. Bucket mining. The mining is to raise the top and bottom from the bottom up, and the upper and lower layers of the mining area are always maintained at about 2m to form inverted steps to protect workers' mining and rock drilling safety. In the easy collapse of the roof, a 1.5~2m pillar should be left within a certain distance to support the surrounding rock of the goaf. The advantage is that the funnel is dense, the blasting ore is in the funnel, and the worker does not need mining or picking. The mining depletion rate is low. However, due to the high height of the ore, the ore is easily broken, there are many broken ore, and the mining loss rate is high. The mining workload is large and the mining cycle is long.
4, shallow hole retention method. The length of the mining area is 50-70m, and two boundary patios are drilled at both ends of the tunnel. The upper and lower sections are connected to each other. The height of each 5m on the patio is drilled to the side or both sides to drill a depth of about 4m, and the tunnel is simultaneously excavated. The patio is generally double-framed.
In the stage boundary patio, sometimes because the lower leveling lane is longer than the upper leveling road, the down-passing patio is adopted, that is, the upper side of the stope is 2m upward, and no ore is terminated, and gradually retreats into the stope. There is a funnel at the bottom of the stope, and the chute is the same as the small middle section. The height is 4~7m, the funnel spacing is 5~7m, and the ore body thickness is less than 8m. Generally, a single row of funnels is arranged on the bottom plate. When 8~12m, a single lane double-row funnel or double lanes are arranged. When the ore body thickness is greater than 12m, it must be arranged. Double transport lanes, three rows of funnels.
The shallow hole retention method is a mining method commonly used in the underground (downhole) mining of fluorite deposits in China. The advantage is that the mining height is low, the high-grade ore is not easy to be broken, the mining workload is small, the cycle is short, and the ore recovery rate can reach more than 80%.
In short, the fluorite mining method is relatively simple. At present, most of the major fluorite mining methods in China use the shallow hole retention method (Table 3).
Table 3 Summary of mining methods for major fluorite mines in China
Third, mineral processing and processing technology
The fluorite beneficiation processing method mainly selects the ore according to the type of ore, the composition of the ore, the grade of the grade, etc., and selects an economically reasonable and technically feasible process. At present, the ore dressing methods of fluorite mines in China include hand selection, gravity (jigging) and floating mineral processing.
Hand selection is mainly used for fluorite and gangue boundaries are very clear, waste rock is easy to remove, various grades of ore is easy to identify with the naked eye fluorite ore. It is the easiest and most economical method of mineral processing.
The manual beneficiation process (Fig. 1) is generally: raw ore → flushing → screening → hand selection. After the sifting and screening, the ore is divided into large blocks, middle blocks and particles (particle size 6~15mm) into the hand selection field. By manual sorting by grade, the grades are piled up, the particles enter the jig jigging, and the debris enters. The flotation plant is processed into a fluorite concentrate.
Gravity (Jig) beneficiation is mainly used to select particle ore with high ore grade and particle size of 6-20 mm. Gravity beneficiation has the advantages of simple structure, convenient operation and remarkable efficiency. It has been widely used in mines with large particle minerals and high grades.
Fluorite lump ore and hand picking reselection is mainly used for metallurgical obtained (called metallurgical grade lump ore).
Floating mineral processing, referred to as flotation. This beneficiation method is widely used in fluorite mines at home and abroad, and is a beneficiation method for obtaining high quality fluorinated (fluorine) concentrate. Whether it is a single fluorite or a symbiotic fluorite ore, whether it is a fluorite ore with a simple ore structure or a complex fluorite ore, whether it is a crystalline coarse grain or a fluorite ore with a finer grain embedded A flotation method can be employed.
At present, China's flotation process is mainly divided into three stages, namely, crushing, grinding and dewatering (Figure 2). Breaking stage
Figure 1 Hand-selected lump ore process flow chart
Figure 2 Flotation process flow chart
The process is generally a three-stage and one-stage closed-circuit process, and small-scale mines also adopt a three-stage or two-stage open-circuit process. In the grinding and floating process, the grinding frequency is determined according to the mineral grain size and the embedding condition. The mineral inlay is fine in size, the ore with difficult monomer separation is secondary grinding, and the other ore can be ground once. The flotation process is determined by the nature of the ore, that is, whether it is a single fluorite or a fluorite ore. The single ore fluorite ore is generally selected by rough selection and sweeping, and then selected 5 to 6 times. The flotation of the (common) fluorite ore is generally the first choice of polymetallic ore, and then the fluorite, the flotation process is the same as a single fluorite ore flotation. A beneficiation agent is used in the flotation process as a collector for useful minerals, an inhibitor of impurities, a pH adjuster, and the like. The flotation reagents generally used in fluorite flotation include oleic acid, soda ash, water glass, aluminum sulfate, and zinc sulfate.
The dehydration process of fluorite concentrate consists of three steps of concentration, filtration and drying. The fluorite concentrate provided for export can be used without a drying process, and only requires less than 10% of water after filtration, and the fluorite concentrate used by domestic manufacturers for producing hydrofluoric acid needs less than 0.5% of moisture after drying.
The fluorite beneficiation indicators of several major flotation plants in China are listed in Table 4.
Table 4 Major fluorite selection plants in China
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