Sedimentary Siliceous Phosphate Rock Ore Dressing Process Example

I. Beneficiation test of Helanshan Phosphate Mine Laboratory

The Helanshan Phosphate Mine is produced in the middle of the Lower Cambrian, and is a sedimentary stratiform phosphorus rock deposit. Its industrial type is siliceous and silicon-calcium ore, the former is the main one. The ore body starts from Suyukou in the north and Dagangou in the south, with a total length of 24 kilometers. Phosphate ore throughout the mining area contains an average of 18% P ₂ O ₅ .

The mineral composition of the ore: useful minerals are colloidal phosphate and apatite (a total of about 40%, a small amount of apatite); gangue minerals mainly include quartz (about 40%), carbonate rock (total of about 9 %, calcite 3%). In addition, there are pyrite (3% to 4%), sericite (3% to 4%) and the like.

The phosphate rock is homogeneously gelatinous, followed by a scorpion, false scorpion, and crumb. The main feature is that the granulated phosphate particles contain impurities of different particle sizes. These impurities are mainly pyrite, limonite, etc., and the particle size is mostly in the range of 0.0065-0.048 mm, and the star-shaped distribution.

The apatite is in the form of fine granular or columnar particles with a particle size of 0.0065-0.026 mm, mainly distributed between the quartz aggregates or the inner edges of the quartz sand chips.

Quartz is scalloped to semi-circular in the form of clastic and invisible grains, ranging in size from 0.08 to 0.16 mm, mostly distributed in sandy phosphate rock and phosphate conglomerate.

The carbonate is mainly dolomite, with a particle size of 0.016~0.528mm, which is mostly produced by rhombohedron or irregular granular aggregate; calcite is mixed in the shape of granularity between dolomite or vein-like output.

The chemical composition of the ore is listed in Table 1.

Table 1 Chemical composition of ore in Helanshan Phosphate Mine

In 1980, the mine was tested in more detail with different processes. The results are summarized in Table 2. . It can be seen from Table 9 that phosphorus concentrates with a grade greater than 30% P ₂ O ₅ and a recovery rate above 80% can be obtained by using Schemes II, III and IV. It is indicated that the selection process of stage grinding and stage flotation is suitable for the mine.

Table 2 Flotation conditions for different process structures

Table 3 Process III Process Conditions Table

Taking Process III as an example, the number and quality flow obtained according to the process conditions listed in Table 3 are shown in Figure 1. The chemical composition of the resulting final phosphate concentrate (concentrate I + concentrate II) is shown in Table 4. Its particle size composition is listed in Table 5.

Table 4 Main chemical composition of phosphorus concentrate (I+II)

Table 5 Final phosphorus concentrate particle size composition (%)

Fig.1 Stage grinding, stage flotation number and quality flow chart of Helanshan Phosphate Mine

According to the phosphorus concentrate product obtained in the flow of Fig. 1, the determination of the degree of separation is performed. The results indicate that: in the first stage of coarse grinding, a part of the phosphorus minerals which have been dissociated by the monomer is sorted first, and then the second stage of the lean continuous body is finely ground to separate it, which is consistent with the granularity of the useful mineral in the ore. First, choose different characteristics of difficulty. Therefore, the operation is convenient and the index is stable. However, it can be seen from the data in Table 6 that in order to obtain a higher quality phosphate concentrate, the fineness of grinding should be below -0.045 mm.

Second, the Lonesome concentrator in Central Florida, USA

Florida is the largest phosphate mine in the United States and the largest phosphate mine in the world. The recoverable reserves are 2.6 billion tons, accounting for about 46% of its total reserves. In 1982, the output of phosphate rock reached 28.061 million tons, accounting for 75% and 23% of the total output of the United States and the world respectively.

Phosphate mining in the region is concentrated in the central and northern regions, with phosphate production in only Polk and Hillsborough counties accounting for 90% of total Florida production. There are 11 companies that mine the central phosphate rock and a company that mines the phosphate rock in the north. Currently, the region has a beneficiation plant up to as many as 24.

The Florida Phosphate deposit was formed during the Neogene to the Miocene, and the distribution ranged from the border of the state to the north and the half of the Nanzhao Peninsula. Mineral deposits of important economic value due to long-term exposure due to weathering are mainly found in the upper part of the northern Hawthorn group and the lower part of the central Bove Valley. In the lithology, the two layers of minerals are very similar, consisting of about one-third of each sand, clay and phosphate in the form of fine or pebbles.

Florida phosphate rock deposit types are: land psephitic phosphate rock, soft and hard phosphate rock, river gravel-like rock phosphate, aluminum phosphate, a phosphorus-containing dolomite Hawthorne layer of six, among them The difference is mainly due to the weathering and/or deposition of the primary ore. The current production of the phosphate rock in Florida is actually derived from the mining of gravel phosphorite.

The terrestrial gravel-type phosphorite ore has a soft texture and is round-oval. The particle size ranges from 25.4 mm to 0.44 mm, and the colors are gray, yellow, brownish green and black. The mineral composition is: 30% to 60% of phosphate, 12% to 25% of quartz sand, and 15% to 40% of clay.

The mining and selection processes used in each concentrator in the Florida area are roughly the same, which can be summarized as three major operations: washing, sorting and clay (tailing) treatment. The specific process is as follows: the topsoil is first stripped with a bucket shovel, the ore is discharged into a panning pit, rinsed into a slurry with a water gun, and pumped to a washing plant. The washing plant is provided with a fixed sieve and a tank washing machine. Equipment such as vibrating screens and hammer crushers . The ore is sieved, washed and classified to obtain a gravel-like phosphate product of about 14% (or +200 mesh) of 30% to 50% of the original ore (the product contains P ₂ O ₅ 30% to 35%, MgO 0.0). %~1%, Fe+Al 2%~3%). The undersize products of less than 14 mesh (or less than 20 mesh) are classified by a hydrocyclone, and the separated -150 mesh slime (containing P ₂ O ₅ to 15%) is discharged into the sedimentation tank; and -14 (or -20) ) ~-150 mesh underflow, that is, as the feed of flotation operation, the Chinese feed and then the "positive-reverse flotation" according to the coarse and fine fractions (that is, the anion collector is floated first to obtain coarse The ore is then subjected to reverse flotation by a cationic collector to remove residual silicon in the coarse concentrate to obtain coarse and fine phosphorus concentrate. This part of the flotation concentrate contains about 30% to 33% of P ₂ O ₅ , 0.0% to 0.5% of MgO, 0.1% to 5% of organic matter, and 2% to 3% of Fe + Al. The flotation reagent species employed, usually caustic soda, ammonia (liquid), sulfuric acid, fatty acid, amine salt, and coal oil, the amount varies depending concentrator. Take the Lonesom concentrator as an example to illustrate the generalization of the Florida phosphate rock by conventional anion-cation positive-reverse flotation.

The Lonersom concentrator was discovered in 1977. It has a design capacity of 249.5 to 27.22 million tons of raw ore per year, and an annual output of 136 to 1.54 million tons of flotation concentrate.

The mine began mining in 1913. The mine is located in the southeast corner of Hillsborough, Florida, about 25 kilometers from Tampa. The reserves of phosphate ore are 50 million tons, and the average P ₂ O _{5 is} close to 32%.

The mineral composition of the mineral is phosphate, quartz sand and phosphated clay, each accounting for about one-third. The main chemical components are: P ₂ O ₅ 9.1%, MgO 0.1%, and the rest are siliceous materials.

The main process engineering of the Lone Som concentrator is described as follows:

The ore mined by a 34m ³ bucket shovel is first prepared as a slurry and then transported to a screening station through a 2286m long pipe. +75mm material waste gas; -75mm+19mm material is crushed and mixed with pulp with a particle size of -10mm. The mixed -19 mm slurry is sent to a Ñ„ 600 mm hydrocyclone via another 610 m long pipe where the phosphated clay is removed and sent to the tailings storage area. The bottom of the hydrocyclone with a concentration of 70% after removal of the clay is discharged directly onto the conveyor belt and sent to the concentrator.

In the concentrator, the delimed material is washed, scrubbed and sieved in a scrubber to produce a final +16 mesh final ovate product (or sieve concentrate). The -16 mesh material is the flotation operation feed. (This part of the feed or the first classification after the coarse, fine-grained level of flotation, or mixed flotation). The feed after being sent to the flotation is first concentrated to a concentration of 75% by a hydrocyclone of Ñ„ 610 mm, and then selected by an anion collector to obtain a foam product (ie, a coarse concentrate); After the cyclone dehydration, sulfuric acid scrubbing and fresh water washing, it is selected with a cationic collector to obtain the product in the tank, which is the final phosphate concentrate. The final phosphate concentrate is dried to 2% moisture, which is the finished product. The tailings obtained in the sorting process are mixed with the clay waste, filtered by natural water, and then covered with the waste rock to form a stable reclaimed surface.

Concentrator flotation system: 4 columns of positive flotation, 2 slots per column. Solvent 14m ³ per tank. The flotation machine model is a Wemco type. The amount of flotation agent is (kg/t feed): fatty acid 1.0, amine salt 0.2, sulfuric acid 0.6, fuel oil 0.6.

According to the washing principle process shown in Figure 2, the sieve concentrate (ie gravel product) contains P ₂ O ₅ 31% to 31.9%, flotation concentrate (ie coarse and fine phosphorus concentrate) containing P ₂ O ₅ 31.9%～33.74%, the content of comprehensive concentrate is MgO 0.3%. The tailings contain P ₂ O ₅ 0.9% to 1.4%. The total recovery rate of concentrate is 75%-85%.

Figure 2 Florida Phosphate Mine Washing Principle Process

For every ton of commercial phosphate concentrate produced by the Lonersom concentrator, about 37.85m ³ of water is needed, of which 95% is recycled water, and only 5% of fresh water is taken from deep wells. Use back water to reduce the consumption of flotation chemicals.

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