Inner Mongolia Bayan Obo rare earth symbiotic mine

    I. Overview

The Baiyun Obo rare earth symbiotic mine is located in Inner Mongolia. The deposit was discovered in 1927 and 1935, we found a rare mineral in iron ore samples. After geological exploration in the 1950s and geological studies in the 1960s, the rare earth reserves in the deposit ranked first in the world.

The Baiyun Obo mining area began construction in 1957. In 1959, the mine provided iron-rich lump iron directly to the blast furnace. Baotou Bayan Obo ore beneficiation processing plant began production in 1965, when the main task is to recover iron ore from ore to meet the needs of Baotou Iron and Steel Company production of iron and steel. At the same time, the rare earth foam in the iron selection process was treated by a shaker, and the low-grade rare earth concentrate containing RE 030% was produced. In 1970, the design of the workshop was re-elected. In 1974, the re-election workshop was officially put into operation. In 1978, a flotation plant for the treatment of re-concentrated concentrates was designed and put into production in 1981. At present, Baotou Steel Concentrator can simultaneously produce two kinds of rare earth concentrates containing RE030% and RE060%, but the recovery rate is low. In 1981, Baotou Iron & Steel Co., Ltd. decided to adopt a new flotation-selective agglomeration beneficiation process for the direct recovery of rare earth concentrates from the ore by flotation to transform the second production series of Baotou Steel Concentrator to improve the recovery rate of rare earths. Two industrial tests in 1984 and 1986 proved that the total recovery of rare earth ore can be increased to more than 45% under the conditions of obtaining two rare earth concentrates containing RE 030% and RE 060%.

  Second, the nature of the ore

Bayan Obo rare earth ore is rare symbiosis of the world rich in rare earth, iron, niobium, fluorite large multi-metal mine. The iron in the ore body is deposited by the Precambrian marine facies. In the Hercynian period, a large amount of hydrothermal fluids of sodium, fluorine, rare earth and strontium associated with biotite granite overlap, causing the original deposited iron ore to undergo hydrothermal exchange. It acts to form a comprehensive deposit of sedimentary-hydrothermal metasomatism.

There are about 71 mineralization elements involved in the Bayan Obo mine, and about 125 minerals have been discovered in the mining area, of which about 15 are rare earth minerals (Table 1). Ore about 90% of a rare earth element to form independent minerals present, and to monazite and bastnaesite-based. The ratio of bastnasite to monazite fluctuates from 3:1 to 1:1 depending on the location of the ore body. Therefore, the Bayan Obo rare earth symbiotic mine is actually a fluorocarbon strontium ore and

Juju mixed mine.

Table 1 Rare earth minerals in the Baiyun Obo rare earth symbiotic ore

The main chemical components and mineral components of a typical ore sample in the Bayan Obo rare earth symbiotic ore are listed in Tables 2 and 3.

Table 2 Main chemical constituents of a typical ore sample of the Bayan Obo rare earth symbiotic ore

Table 3 Main mineral components of a typical ore sample of the Bayan Obo rare earth symbiotic ore

The particle size determination of rare earth minerals in the Bayan Obo rare earth symbiotic ore (Table 4) shows that the crystal size of the two main rare earth minerals, bastnasite and monazite, in the ore is relatively fine, in the above -0.04 mm class. The amount of two rare earth minerals accounted for 52.94%. The relationship between the different fineness of grinding and the dissociation degree of rare earth minerals (Table 5) shows that the symbiotic relationship between rare earth minerals and iron minerals and fluorite in ore is very close; when the fineness of grinding reaches 95% of -325 mesh, The monomer dissociation degree of rare earth minerals reached 90.10%.

Table 4 Particle size of major rare earth minerals in the Bayan Obo rare earth symbiotic ore

Table 5 Relationship between different grinding fineness and the dissociation degree of rare earth minerals

  3. Flotation-re-election-flotation process and indicators for recovery of rare earth minerals from Baotou Steel Concentrator

Baotou Steel Concentrator is still a selective plant for the recovery of iron concentrate. The -200mm raw ore transported from the mine to the concentrating plant is crushed to -25mm in two stages and sent to the grinding and selection workshop. After a rod mill, two-stage ball mill and grading closed circuit, it is ground to -200 mesh 85%~90%. Separate by two different principle processes. Process I: first obtain the magnetite concentrate by weak magnetic separation, then carry out part of the fluorite flotation, and then carry out coarse selection and selection of the rare earth, and obtain the rare earth foam containing RE015%~17% for reprocessing workshop, rare earth Rough-selection of tailings and selected medium-mineral mines for iron ore selection; Process II: In order to reduce the fluorine and phosphorus content in iron concentrates, flotation is used to float some of the fluorite, followed by rare earth rough selection and selection. The rare earth foam delivery re-election workshop containing RE0.15%~17% is obtained, and the rare earth rough-choice tailings and the rare earth selected medium ore are combined and sent to the iron selection operation.

The rare earth foams of all series of the whole plant are concentrated and sent to the re-election workshop for treatment. The concentrates of the rough selection shaker and the sweeping shaker are combined and sent to the rare earth flotation workshop for treatment. After sweeping the middle of the shaker, the concentrate is sent. The sweeping operation of the flotation workshop. After re-selection of rare earth concentrates by flotation workshop, RE060% rare earth concentrates and REO 30% rare earth concentrates were obtained. The flotation-re-election-flotation process for recovering rare earth minerals from Baotou Steel Concentrator is shown in Figure 1.

Figure 1 Float-heavy-flotation process for recycling rare earth minerals in Baotou Steel Concentrator

The agent system for rare earth flotation in the iron selection process is listed in Table 6. The flotation agent system containing REO 60% rare earth concentrate and RE030% rare earth concentrate is selected in the table. 7.

Table 6 Rare Earth Flotation Pharmacy System in the Iron Separation Process

Table 7 Re-election of rare earth concentrate re-flotation agent system

The rare earth beneficiation indexes for each sorting operation of the flotation-re-election-flotation process are listed in Table 8, Table 9, and Table 10, respectively.

Table 8 Rare Earth Flotation Foam Sorting Indicators

Table 9 Rare Earth Re-concentration Concentrate Selection Index

Table 10 Selection criteria for re-election of rare earth concentrates for re-flotation

The main equipment list of the rare earth re-election flotation workshop is shown in Table 11.

Table 11 List of main equipment for rare earth re-election-flotation workshop

   4. Flotation-selective agglomeration beneficiation process and industrial test indicators for comprehensive recovery of rare earth and iron minerals

The flotation-selective agglomeration beneficiation process is based on the summarization of domestic and foreign research work, and is newly formulated for the characteristics of the Baiyun Obo rare earth symbiotic ore. Raw ore grinding to 95%-200 mesh, using sodium carbonate, water glass, oxidized paraffin soap for rare earth, vermiculite mixed flotation, and separating it from iron and iron-containing silicate minerals; rare earth, fluorite mixed flotation foam Washing, concentrating and removing the drug, using sodium carbonate, water glass, sodium fluorosilicate, C _{5 ~ 9} ammonium citrate combination agent to preferentially float the rare earth minerals to separate them from fluorite, barite, calcite and other minerals; After the rare earth coarse concentrate, it is delimed, de-pulped and selected with sodium carbonate, water glass, sodium fluorosilicate, C _{5 ～ 9} and hydroxamic acid to obtain RE060% rare earth concentrate and RE030 respectively. % rare earth concentrate, the total recovery of rare earth is more than 45%; the tailings of rare earth and fluorite mixed flotation are finely ground to -400 mesh in sodium hydroxide and water glass medium, using the ore itself. A new technology for selective agglomeration of hematite by fine-grained magnetite, which is separated from iron-containing silicate minerals by four times of deliming to obtain iron content of 61%, fluorine content of 0.45%, and iron recovery rate of 80% or more. The selection indicator.

The flotation-selective agglomeration beneficiation process is shown in Figure 2. The pharmaceutical system and dosage of the process are listed in Table 12. The selection criteria for industrial tests are listed in Table 13.

Figure 2 Flotation-selective agglomeration beneficiation process

Table 12 Flotation-selective agglomeration beneficiation process pharmacy system and dosage

Table 13 Process test indicators for flotation-selective agglomeration beneficiation process