Treatment Of Waste Acid And Recovery Of Arsenic Which Containing Arsenic And Fluoride

This topic is targeting on find a comprehensive technology to realize the dispose and resource utilization of arsenic-fluoric waste acid,(which contains 2531 mg/L arsenic,11490 mg/L fluorine etc).This waste acid comes from the purification process of Acid-making with Smelting Gas in Daye Nonferrous Metal Company.The comprehensive technology includes utilization of arsenic,utilization of fluorine and treatment of residual waste acid.By this process,both arsenic and fluorine resources were recovered to produce arsenic trioxide that meet YS/T 99-1997 quality standards and cryolite that meet GB/T 4291-2007 quality standards.Even after the comprehensive technology the waste acid was qualitied for the GB 25467-2010 standards.This paper emphasized on two aspects including the recycling of arsenic from waste acid and the design of the integrating processing device for the waste acid.During the research in recycling of arsenic from waste acid,the creative process “precipitation – ball-milling – acid leaching – reduction – crystallization” was adopted.During the precipitation process,when the p H is 9,Cu/As is 1.5:1,reaction temperature is 30?,reaction time is 40 min,the precipitation rate of arsenic can reach 95.3%.During the ball-milling process,when the ratio of grinding media to material is 4:1,ball-milling time is 30 min,and the rotated speed is 350 r/min,the average size of copper arsenic is 2 ?m.Meanwhile,the size of the copper arsenic decreased after ball-milling process,leading to increasing the leaching efficiency of arsenic.During the acid leaching process,when the sulfuric acid concentration is 5%,liquid-solid ratio is 4:1,reaction time is 30 min,the leaching efficiency of arsenic is around 95.6%.During the reduction process,when the gas flow is 16 L/h,reaction temperature is 60?,reaction time is 30 min,the recovery of arsenic is 94.7%.During the crystallization process,when the p H is 1,crystallization temperature is 20?,the purity of arsenic trioxide is 95.8%.In conclusion,after the arsenic utilization process,the arsenic concentration was reduced to 45.2 mg/L and the fluorine concentration reduced to 10260 mg/L.Next,the settlement is utilization of fluorine and treatment of residual waste acid.In addition,according this integrated treatment process,a set of 300 L/h integrated device for the treatment of arsenic-fluoride waste acid was designed.After the treatment of “precipitation – ball-milling – acid leaching – reduction – crystallization – synthesis – neutralization – flocculation”,the fluorine concentration was 5.42 mg/L,arsenic concentration was 0.27 mg/L,for which was qualified the GB 25467-2010 standards.The result in verifying the industrialization feasibility of this device indicats that: the average annual sales income 362 thousand yuan,and the average annual total cost is 336 thousand yuan.All the investments can be recovered after two years of production.Hubei science and technology support research project — research and demonstration classes(2015BCA249)after the series studies of “arsenic utilization process – fluorine – acid treatment process”,the high added-value utilization of precious resources is realized,and the unity of environmental benefit,economic benefit and social benefit is achieved.