Experimental study on recovery of rare earth from Baotou Steel Mine

Main current iron ore mined clouds, the average content of rare earth oxide in the iron ore East more than 5%, the amount of rare earth oxide that is entered in the clad mineral processing 40 tons. At present, Baotou Steel mainly recovers rare earth concentrates from strong magnetic ore and strong magnetic tailings produced by the oxidizing ore process of the ore dressing plant. The rare earth minerals in other products are basically not recycled, and the rare earth recovery rate is less than 10 in the entire separation process. %. The total tailings of Baotou Steel Concentrator are all sent to the tailings pond for storage. Rare earth is the most important resource in tailings, and the value of rare earth accounts for more than 70% of the total resources. The rare earth industry is a rare and advantageous industry in China. The output of rare earth products in China has reached more than 90% of global production. Rare earth new materials have become an indispensable main material for the development of China's high-tech industries. Rare earths are regarded as strategies by developed countries. The storage and protection of resources, how to use and protect China's rare earth resources to provide guarantee for the long-term development of China's economy is an arduous and important task for a long period of time now and in the future, especially Baotou rare earth resources, which account for more than 80% of the country. .

Therefore, it is very urgent and significant to recycle the rare earth minerals in the tailings of Baotou Steel Concentrator.

First, the nature of the sample

The ore samples used in the samples were taken from the Baotou Steel tailings dam. The results of multi-element analysis and mineral composition analysis of the ore samples are shown in Tables 1 and 2, respectively.

Table 1 Multi-element analysis results of tailings dam tailings /%

Table 2 Analysis results of mineral composition of tailings dam tailings /%

It can be seen from the analysis results that the rare earth content in the ore sample is slightly higher than the average content of rare earth oxides in the dolomite or east ore iron ore, and has a high selectivity. In addition, the content of iron and fluorite in the ore sample is relatively high, and it also has good recycling value.

Second, the study of the test process

According to the characteristics of Baotou Steel Tailings and the research of the ore dressing process of Baiyun Obo, the experimental process is determined as a mixed flotation-preferred flotation-magnetic separation (flotation) process.

(1) Mixed flotation

The purpose of mixed flotation is to first divide the useful minerals in the tailings into two parts by flotation: easy flotation minerals and difficult flotation minerals. Easy to mix a foam concentrate flotation rare earth minerals, fluorite, apatite, barite, flotation tailings are mixed concentrated mineral flotation hard iron and niobium. This provides favorable conditions for the recovery of each single mineral in the future. The agent used is the anti-floating collector GE28, which is subjected to a rough selection and secondary selection and four selections. The test results are shown in Table 3.

Table 3 Mixed flotation test results /%

From the analysis results, it can be seen that: (1) The recovery rate of rare earth and fluorine in the mixed foam reaches more than 96.00%, which provides a resource basis for recovering rare earth and fluorite from the mixed foam; (2) rare earth in the mixed flotation tailings and The fluorine content is very low, 0.73% and 1.02%, respectively, which provides favorable conditions for the later recovery of iron and strontium.

The mixed foam is selected for drug removal, preferably a portion of fluorite, enriched in rare earth.

The mixed foam is subjected to one rough selection, five closed-circuit selections, and an unequal amount of water glass is added in stages. The results are shown in Table 4.

Table 4 Mixed foam after a rough selection of five closed-circuit selection results /%

It can be seen from Table 4 that: (1) the rare earth occupation rate of fluorite enrichment is 14.96%, the fluorite occupation rate is 49.87%, the rare earth grade is low, and the fluorite grade is high, which is beneficial to fluorite recovery; (2) rare earth The rare earth occupancy rate in the enrichment reaches 85.00%, and the grade is also improved, which is beneficial to the recovery of rare earths. The grade of fluorite is not low, and the occupation rate is about 50%. It is also necessary to recover fluorite after rare earth recovery.

The rare earth Occupancy in the fluorite enrichment is only 15% of the rare earth in the mixed foam, and the grade is not high, but it can also be recycled. The recovery process is relatively simple, as long as it is once rough-selected, and its product is rare earth enrichment. The taste is about 15%. Sorting high-grade rare earth concentrates, the test results and process flow are shown in Figure 1.

Figure 1 Flotation rare earth process in fluorite enrichment

It can be seen from Fig. 1 that after a rough selection, the recovery rate of rare earth can reach 76%-90%, and the rare earth grade of rough-selected concentrate is 14.09%-15.83%.

(2) Separation of rare earths

Before the rare earth enrichment is sorted, the magnetic separation de-ironing test can be carried out to further improve the grade of the rare earth enrichment, thereby making the rare earth separation effect more ideal. After strong magnetic de-ironing, the rare earth enrichment with REO of 15.15% was selected by three times of rough selection, and a high-grade rare earth concentrate containing 60.72% REO was obtained. The rare earth oxide in tailings was 1.79%, the recovery rate of rare earth operation is 90.39%. The process flow chart is shown in Figure 2. The complete process flow chart for tailings selection of rare earth is shown in Figure 3. The main data are listed in Table 5.

Note: The final total recovery of rare earth concentrate is the product of the recovery rate of rare earth in the fluorite mixed foam of 96.32% and the recovery rate of rare earth flotation of 90.39%. The final total recovery is 87%.

Figure 2 Rare earth separation process

Figure 3 full process flow

Table 5 Results of rare earth test from rare earth enrichment /%

Third, the conclusion

(1) It is seen from the experimental research results that the process of recovering rare earth from tailings is feasible and can fully meet the standards required for production.

(b) As can be seen from this process, many useful minerals such as iron, antimony and fluorite in the tailings are recyclable and provide favorable conditions for further recovery of useful minerals.

(3) Providing a reference for the rational utilization of tailings resources and solving the problem of tailings accumulation.

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