Recovery Of Gallium From Fly Ash: An Experimental Study

Gallium is the indispensable materials in high technology fields, because of its use as semiconductor and optical materials. With the development of the application, the demands for it has increased in recent years. Gallium is not mined itself, as it appear very widely dispersed on the earth's surface. Rather, it is produced from several non-ferrous refinery residue, together with zinc, lead, aluminum. It is usually present in small amounts compared to similar metals(Zn, Al) since the major sources of it is those acidic sulphate or chloride solutions from hydrometallurgical production of zinc or Bayer solution of aluminum. Recoveries of it from aqueous solutions can be mainly achieved by solvent extraction. However, solvent extraction is frequently limited to industrial applications because of several economical technical and environmental constraints, including low extraction efficiency, high consumption of extraction, complicated extraction process, extraction dispersion, loss of solvent, and pollution impact. Thus, new separation technologies which can separate and recover gallium from different primary and secondary sources by high-effective, low-cost and environmental friendly way are of great importance. A kind of extraction resin separation and recovery method for separation gallium(III) was reported in this paper. The aim of the research is to collect preliminary results for a pilot-scale production.Because there is a small amount of useful distributing rare elements in the fly ash, for instunce, Galliun, Germanium, Vanadium,etc. the feasible condition of the extraction and saparation of gallium from the fly ash will be discussed in this thesis.With above-said the fly ash as raw materials, orthoonal table was use for arranging the test, a few number of more representative tests can be selected for obtaining optimun or more excellent experimintal conditions. The lixiviumis 6 mol/1 HCl and the ration between solid and liquid is 1:40. Using the method of extremely difference analysis for dealing with the test results and the optimum condition had been obtained.The optimum experimental condition extracting gallium from fly ash is that 5gair dried sample is laid into an ash wave, then put it into Muffle furnace for 30 minutes voasting at 830°C; added 6 mol/l and 40ml of HCl solution, heated in a boiling-water baths for 6h , the extraction efficiency of gallium under this condition is more than 80%.The results show that the polyurethane foam has high adsorption capacity for Ga in 6mol/l of HCl solution with a saturated the adsorption capacity of l-2.1mg/g, and the adsorption rate of 85.12% and the desortion rate of 88.15%,the polyurethance foam can be reused circularly.In the course of gallium determining, the colorimetric method was used for the analyzing of gallium.