JAS COAT固化剂对磷石膏环境风险的影响

Impact of JAS COAT on the environmental risk of phosphorus gypsum

磷石膏是湿法生产磷酸的副产物,大量堆存的磷石膏给环境造成了巨大的压力。通过室内理化性质试验研究了JAS COAT固化剂对磷石膏性能的改良,优选出适宜的JAS COAT固化剂掺量及含水率,并对稳定化机理进行了探讨。结果表明,加水及固化剂不能改变磷石膏中重金属的总量,但明显降低了浸出液中重金属的质量浓度;固化剂掺量为3%~5%时,磷石膏的放射性随含水率增加呈先减小后增大的趋势。

In this paper,we have made a thorough exploration of the JAS COAT by choosing it as a treating agent to stabilize the treatment of phosphogypsum and the effects of different dosages of treating agents in hoping to improve the performance of phosphogypsum while discussing the stabilization mechanism through a series of laboratory tests on the physicochemical properties. As a matter of fact,phosphogypsum（ PG） is a byproduct from the manufacturing process of phosphoric acids with the ＂wet acid method＂. However,it remains a severe problem faced by the phosphorus chemical industry on how to stack the large amount of such byproducts. Therefore,what remains for us to explore further is to investigate and establish a new technology for the onsite disposition of the phosphogypsum in a large scale and make it possible to utilize the phosphogypsum resource and innocuity treatment of phosphogypsum so as to reduce the environmental pollution caused by phosphate industry. The results of our experimental tests over the phosphogypsum have shown that what we have done has not changed the total amount of heavy metals in the phosphogypsum by adding water and a curing agent,though the content of heavy metals in the leachate has been found decreased approximately with the increase of JAS COAT additives. For example,when the JAS COAT content keeps at 4. 5%- 5%,the water content should be increased by a rate of 9% to 14%. But,when the content concentration rate of Hg,Cd,Cr,Pb,As and Ni in the leachate reaches the minimum limit and then decreases by about 90%,as compared with the control group,the Radon concentration and radioactivity may tend to decrease approximately so as to come nearer to the GB 16889—2008 criteria limit on the Ⅲ grade in GB 3838—2002 for the leachate and water quality standard. Nevertheless,with the increase of JAS COAT additives,for example,when the JAS COAT content is 4. 5% and the water content concentration is 10%,the radon concentration and the external exposure index can be expected to drop to the lowest rate,approximately to 7% and 57%,respectively,than when they are not treated. Furthermore,when the JAS COAT content is4. 5% and the water content is 8%,the internal exposure index can be expected to drop to the lowest,which demonstrates an approximate reduction of 53% than that in the case of being untreated.