Study on the Treatment of Liquid Waste from Rare Earth Processing by Chemical Precipitation

Tin Moe Hlaing, Aye Thi Tar, Thant Zin Myo, Bo Bo Mya Win

Abstract


This paper describes treatment of liquid waste from rare earth processing by chemical precipitation. Monazite ore from Moemeik Myitsone area was used as raw material for rare earth processing. Large amount of solid and liquid wastes were generated after rare earth oxide processing. Solid waste was stored in the storage tanks and liquid waste needed further treatment before discharges to the environment. Research process serves the purpose of reducing the volume of the waste as much as possible to protect men and the environment from any undesirable effects for the present and future generation. Treatment methods are selected based on the composition, quantity and form of the waste materials. The used method is chemical precipitation method. For liquid waste treatment, the most coagulation treatment used is the Fe +++ co-precipitation followed by settling, decantation and filtration of the supernatant liquid. The efficiency of the process can be improved by careful control of the pH and the settling the decantation procedure. The sludge was filtered, dried in oven and collected in plastic bags and temporary stored in 100 liters plastic drums.   Finally all of the decontaminated effluents are safety discharged to the environment. All of the experiments were analyzed by the X- ray Fluorescence Spectrometer (XRF). Before treatment, thorium and uranium contained <2000 ppm,  < 300 ppm and this is in the low level waste. After treatment result in decant water gives uranium (< 1 ppm) and thorium (< 10 ppm).

According to the threshold limits for the UK radioactive classification system,   liquid waste from rare earth processing was less than (0.4 Bq/g) and this range is in exempt waste and can be discharge to drain and to the environment safety. The safety regime was in place and improved simultaneously by survey monitoring by using Alert Monitor 4 meter Scale in USV/H.


Keywords


rare earth processing; chemical precipitation; coagulation; co-precipitation; settling; decantation; filtration; decontaminate; effluents; sludge; discharge; x-ray fluorescence spectrometer; alert monitor.

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References


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