2016 2nd International Conference on Sustainable Energy and Environmental Engineering (SEEE 2016) ISBN: 978-1-60595-408-0

Study on New Desilication Technology of High Silica

Hai-yun XIE 1, Chao DING 1, Peng-fei ZHANG 1,2 , Lu-zheng CHEN 1, and Xiong-TONG 1 1Faculty of Land Resource Engineering, Kunming University of Science and Technology, Kunming 650093, China 2State Key Laboratory of Complex Nonferrous Metal Resource Clean Utilization, Kunming 650093, China

Keywords: High silicon bauxite, Desilication, Gravity separation, .

Abstract: There are abundant diasporic bauxite resource in China. The gravity separation and flotation process are utilized for treating this kind of . When the ore grinding fineness is -200 mesh 80%, the qualified bauxite concentrate can be obtained, and it contains Al 2O3 71.62%, SiO 2 8.94%, and its Al 2O3 recovery rate is 75.43%, A/S is 8.02.Compared with single flotation process, it can be reduced for the dosage flotation reagent and the cost of processing.

Introduction China's bauxite resources are rich, the amount of resources of 1.914 billion, ranking the fifth in the world, but more than 80% are medium and low grade ore, Aluminum silicon ratio (A/S) between 4 to 7 of the bauxite accounted for 59.5%. These can not meet the basic conditions for the production of alumina by Bayer process. (A/S>8) [1]. The vast majority of China's bauxite belong to high-alumina, high-silicon, fine-grained embedded diaspore-type bauxite, so the bauxite is difficult to concentrate. At present, there are three kinds of methods used in our country, which mainly include physical removal of silicon, chemical removal of silicon and biological removal of silicon. Because aluminum has important economic value, a large number of bauxite resources in China are widely used in flotation-Bayer combination method to produce aluminum [2-3]. Compared with chemical and biological removal of silicon, physical removal of silicon has many advantages, such as low cost, low energy consumption, easy to improve the ratio of aluminum and silicon, easy to realize industrialization and so on, and it has broad application prospects [4].

Ore Raw Material Bauxite ore samples taken from Zhaotong of Yunnan. The results of multi-element analysis of bauxite ore in Table 1. From the results of multi-element analysis, it can be seen that the ore belongs to high-alumina, high-silicon and low ratio of aluminum- silicon ore, with lower iron content and a certain amount of rutile and less other impurity metals. Phase analysis shows that the ore is diaspore type bauxite, the main mineral is kaolinite and muscovite, in addition to containing a small amount of anatase and quartz. Table 1. Results of multi-element analysis of bauxite ore.

Mineral Al O SiO Fe O TiO CaO MgO K O Na O S P Composition 2 3 2 2 3 2 2 2

content(%) 67.05 12.42 0.85 2.67 0.035 0.038 1.56 0.14 0.025 0.018

Experimental Method Flotation experiment reagents mainly include sodium carbonate, sodium silicate, sodium

hexametaphosphate, lead acetate, sodium oleate, 2 #oil(pine alcohol oil) and so on, These agents are of analytical grade. The main equipments and instruments are XMQ-240×90 conical ball , XFD single flotation machine (1.5L), DL-5C disk vacuum filter, 101-3 constant temperature drying oven, LL-600×360 spiral chute. The gravity separation and flotation combined method were used in this experiment, and this paper is aim to decrease silicon and improve the ratio of aluminum to silicon in the bauxite ore.

Results and Discussion

The Gravity Separation Desilication of Bauxite

The spiral chute work the slurry concentration is 5%; The spiral chute roughing and concentration test processes are shown in Figure 1, The spiral chute roughing and concentration test results are shown in Table 2.

Figure 1. The flow chart of spiral chute roughing and concentration.

Table 2. The results of spiral chute roughing and concentration.

Productivity Grade(%) Recovery(%) Product Name A/S (%) Al 2O3 SiO 2 Al 2O3 SiO 2

concentrate 1 41.49 7.38 70.23 9.52 43.41 30.20 middling 1 4.70 5.10 67.32 13.20 4.71 4.74 middling 2 5.97 4.90 66.98 13.67 5.96 6.24

middling 3 5.79 4.62 65.73 14.23 5.67 6.30 slime 42.05 3.93 64.26 16.34 40.25 52.52 run-of-mine 100.00 5.13 67.13 13.08 100.00 100.00

It can be seen from table 2, when the bauxite ore grinding fineness is -200 mesh 80%, through a roughing and a concentration by spiral chute, Al 2O3 concentrate grade is 70.23%, SiO 2 concentrate grade is 9.52%. The yield of concentrate is 41.49%, and the recovery is 43.41%. the concentrate of the A/S is 7. Closed-Circuit Desilication Test of Gravity Separation and Flotation for Bauxite According to the spiral chute roughing and concentration tests, the following closed-circuit process was used and shown in Figure 2, the results are shown in Table 3.

Figure 2. The flow chart of gravity separation and flotation for bauxite ore.

Table 3. The results of gravity separation and flotation. （ ） （ ） Productivity Grade % Recovery % Product Name A/S （%） Al 2O3 SiO 2 Al 2O3 SiO 2

gravity concentrates 44.65 7.25 70.32 9.70 46.83 34.87

flotation concentrates 25.97 9.69 73.85 7.62 28.60 15.93

total concentrates 70.62 8.02 71.62 8.94 75.43 50.80

29.38 2.70 56.07 20.80 24.57 49.20

ore 100.00 5.40 67.05 12.42 100.00 100.00

As shown in Table 3, the total concentrate yield is 70.62%, the grade of concentrate is Al 2O3 71.62%, SiO 2 8.94%, the Al/Si ratio is 8.02, and the recovery of Al 2O3 is 75.43%. It can be seen that a qualified bauxite concentrate will be obtained by the combined- process. Compared with simple flotation process, it has many advantages, such as low production cost, low flotation reagents consumption, little pollution to the environment and etc.

Conclusion

(1) The bauxite samples are relatively high in aluminum and silicon, and its component is Al 2O3 67.05%, SiO 2 12.42%, and A/S is 5.40. Diaspore is the main valuable mineral in the ore, gangue minerals are kaolinite, muscovite, quartz and so on.

(2) When the bauxite ore grinding fineness is -200 mesh 80%, through a roughing and a concentration by spiral chute, bauxite concentrate contains Al 2O370.23%, and the recovery is 43.41%. the concentrate of the A/S is 7. (3) The results of this study is admirable by gravity separation and flotation process, the total concentrate production rate is 70.62%, the grade of bauxite concentrate is Al 2O3 71.62%, containing SiO 2 8.94%, the Al/Si ratio is 8.02, and recovery of Al2O3 is 75.43%. This study has provided a potential method for the exploration of bauxite ore.

Acknowledgements This work was financially supported by the Natural Science Foundation of China (Grant No. 51464030, No. 51564028).

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