Mr. Ding Daoheng July 1927 to examine the way the iron ore found in the northwest, in 1935, Professor He Zuolin found rare earth minerals in ore samples retrieved in Mr. Ding Daoheng. After the founding of the People's Republic of China, the 241 Geological Team of the North China Geological Bureau conducted a detailed survey of the main and eastern mines, and determined the iron ore and rare earth reserves, indicating that Baiyun Obo is a large iron ore and a large-scale rare earth deposit.
First, the nature of the ore
Baiyunebo sedimentary deposits based header metamorphic - hydrothermal account of iron, rare earth metal, niobium multiple symbiotic large deposit, was found to have 71 kinds of elements, more than 170 kinds of minerals, ores many types, wherein the largest in the world reserves of rare earth, rare earth minerals There are about 15 kinds, but mainly fluorocarbon antimony or monazite light rare earth mixed ore, the ratio is 7:3 or 6:4, accounting for about 80% of the national rare earth reserves. The symbiotic relationship between the useful minerals is close, the size of the inlaid cloth is fine, and the particle size of the rare earth mineral is generally between 0.01 and 0.074 mm. The useful minerals in the ore are magnetite, hematite, bastnasite, monazite, and strontium minerals. The main gangue minerals are smectite, sodium amphibole, calcite , dolomite, barite , and apatite. Stone, quartz , feldspar, etc.
The chemical composition of Baotou Iron Oxide Ore is shown in Table 1.
Table 1 Table of main chemical compositions of Baotou Mine iron oxide ore (%)
Second, rare earth mineral processing production process
Since the 1960s, the state has conducted many scientific and technological researches on the iron, rare earth and antimony beneficiation organizations of the Baiyun Obo iron oxide ore. It has studied more than 20 kinds of mineral processing processes in detail. In 1990, the Changsha Research Institute of Mining and Metallurgy cooperated with Baotou Steel to successfully carry out industrial tests using two series of weak magnetic separation-strong magnetic separation-flotation recovery of iron and rare earth process to transform Baotou Steel Concentrator. The process is fully successful. It embodies the guiding ideology of “iron-based, comprehensive recovery of rare earth mineralsâ€.
Baotou Steel Concentrator has built eight production series (5 of which are treated with oxidized ore and 3 of which are treated with primary ore). The annual processing of raw ore is 9 million tons, and the annual production of iron concentrate is 3.5 million tons. 40,000 tons (REO). The iron oxide ore beneficiation series firstly grinds the original ore to -0.074mm, accounting for 90% to 92%, and the weak magnetic separation selects the magnetite. The tailings are coarsely selected under the condition of strong magnetic separator magnetic induction strength 1.4T, which will be red. The iron ore and most of the rare earth minerals are selected into the strong magnetic coarse concentrate. The coarse concentrate is selected by a strong magnetic (0.6-0.7t), and the strong magnetic selected iron concentrate and weak magnet concentrate are combined and sent to the anti-floating. Select and remove gangue minerals such as fluorite and rare earth with magnetic separation to obtain qualified iron concentrate. Strong magnetic medium ore (selected tailings) containing REO 9% to 12%, rare earth recovery rate of 25% to 30% as flotation rare earth raw materials, using H 2 O 5 (o-hydroxynaphthyl hydroxamic acid), water glass, J102 ( Foaming agent), a flocculating rare earth mineral in a weakly alkaline (pH9) slurry, and a mixed rare earth concentrate (carboncarbonite and monazite) grade 50 after one rough selection, one sweep, and second selection. %至60%, average 55.62%, rare earth recovery rate of 12.55%; rare earth concentrate level of 34.49%, rare earth recovery rate of 6.1%, total rare earth recovery rate of 18.56%, for strong magnetic medium ore The recovery rate of flotation operation is 72.75% (the grade of rare earth concentrate is adjusted according to market demand). The process of rare earth beneficiation is shown in Figure 1.
Fig.1 Process flow of flotation of rare earth minerals in strong magnetic separation of Baotou Bayou O Mine
3. Innovation and development of rare earth mineral flotation reagents
Before 1975, rare earth mineral flotation collectors used fatty acid collectors. The rare earth minerals in Baotou ore were associated with fluorite, calcite, barite, hematite, etc., and these minerals floated when flotation of rare earth minerals. It is difficult to separate, preferential flotation rare earth or mixed flotation-separation of rare earth minerals can only obtain rare earth concentrate containing about 20% REO. In order to obtain high-grade rare earth concentrate, the tailings of the ore weak magnetic separation magnetite are subjected to semi-preferred semi-mixed flotation [adding NaOH, Na 2 SiO 3 , and oxidized stone soap combination agent in strong alkaline pulp ( pH11) preferentially flotation of fluorite, barite and other easily floating minerals, and then add Na 2 SiF 6 activated rare earth minerals (mineral pH 8 ~ 9) to the slurry, and float the rare earth and part with the oxide wax Fluorite], the rare earth foam of the mixed flotation is re-elected by a grooved slime shaker to obtain a re-selected rare earth concentrate containing about 30% REO. The re-election concentrate, such as the reuse of fatty acid collectors, has little effect on flotation selection. Therefore, from 1966 to 1978, Baotou Steel Concentrator could only produce rare earth concentrates containing 20% ​​to 40% of REO for rare earth smelting, thus affecting the effective development of China's rare earth smelting, extraction, separation and application industries. status. The chemical composition of the re-selected rare earth concentrate is shown in Table 2.
Table 2 Table of chemical composition of re-selected rare earth concentrates (%)
At the end of 1975, the Nonferrous Metal Research Institute Guangdong Branch used large amounts of water glass to suppress gangue minerals (Na 2 CO 3 as pulp pH adjuster and Na 2 SiF 6 as rare earth minerals) in the laboratory flotation re-election of rare earth concentrates. Agent), using C5-9 hydroxydecanoic acid to float rare earth minerals, made breakthrough progress, and obtained rare earth concentrate containing REO >60%.
In October 1976, a semi-industrial test of 30 t/d was carried out at Baotou Nonferrous Metals Plant, which verified the results of small tests. Since then, the prelude to the production of high-grade rare earth concentrates from the Baiyun Obo ore has been opened.
Due to the weak ability of C5-9 hydroxydecanoic acid to collect, it requires multiple sweeps and the drug is not stable in production. In 1979, Baotou Metallurgical Research Institute successfully developed cycloalkyl hydroxamic acid (used as a ring raft when used). Ammonium acid), applied in industrial production at the end of the year, adopts a coarse and fine closed circuit process. When the ore (re-elected concentrate) grade is 3.82%, the rare earth grade can be produced as 63.74%, and the flotation operation recovery rate is 66. 75% of rare earth concentrate. From 1979 to 1985, the production of rare earth concentrates with cycloalkyl hydroxamic acid was good, but the selectivity of cycloalkyl hydroxamic acid was also poor during the production process, and there were many kinds of adjusting agents. Sodium fluorosilicate is inconvenient to use; in 1985, Baotou Rare Earth Research Institute (former Baotou Metallurgy Institute) successfully developed H 2 O 5 (o-hydroxynaphthyl hydroxamic acid) collector. The test results show good selectivity to rare earth minerals. , greatly simplifying the flotation reagent system, only need to add water glass, pulp flotation pH9 or so, in July 1986 in the concentrator for industrial trials, using a coarse and fine closed circuit process, when the ore (re-election concentrate) grade At 23.12%, a rare earth concentrate with a grade of 62.32% and a recovery rate of rare earth flotation operation of 74.74% can be obtained. Hydroxamic acid (hydroxamic acid) can form stable five-membered ring conjugates with transition metal ions such as rare earth, cerium (strontium) and iron. Therefore, hydroxamic acid (salt) acts as a collector rather than fatty acid (salt). The rare earth minerals have high selectivity and high flotation recovery.
The production results show that the non-polar group of hydroxamic acid has a great influence. H 2 O 5 has better effect than alkyl hydroxamic acid, and may form π•π conjugated double bond mainly with aromatic hydrocarbon hydroxamic acid. The density of electron clouds on the bonded atom "O" is stronger than that of the alkane hydroxamic acid.
Since H 2 O 5 needs to be added with a large amount of alcohol, it is required to add ammonium hydroxide to form o-hydroxynaphthyl ammonium hydroxide, which is complicated to be prepared in the production workshop, and the solid particles of H 2 O 5 cannot be safely and efficiently dissolved. The formation of ammonium salts, 1992-1994 Baotou Steel Rare Earth Research Institute (former Baotou Rare Earth Research Institute) successfully developed H316 (H 2 O 5 based improvement) instead of H 2 O 5 , combined with water glass, foaming agent J103 (Pulp slurry pH 7～8) was tested in industrial test. The comparison of H 3 16 and H 2 O 5 industrial test results showed that H316 had an improved recovery rate of 10.09% than H 2 O 5 when the grade of rare earth concentrate was the same (53%). And H316 does not need to use ammonia to dispense with the drug, which improves the working environment. The cost per ton of rare earth concentrate is reduced by 44.22 yuan, and the cost of chemicals is reduced by 7.13%.
It fully demonstrates that with the continuous improvement and innovation of rare earth flotation reagents, it promotes the development of rare earth mineral processing technology in China, and at the same time makes the technology of rare earth flotation in China reach the international leading level.
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