Research On Process Of Recycling Copper And Zinc From Spent Catalyst Of Methanol Synthesis

Spent catalysts is a kind of solid waste, the purpose of recycling utilization of them is to reduce environmental pollution and save resources. At present, China’s methanol production capacity is about 70 million tons/year. Generally, methanol synthesis catalyst is very sensitive to sulfur which is a poisoning substance. Every year 13.7 to 17.2 thousand tons of new spent catalysts are produced in methanol synthesis processes. As we known, the spent methanol catalyst contains a high concentration of copper and zinc metal elements. To achieve sustainable development, recovery of copper and zinc compounds from spent catalysts can not only obtain certain economic benefits, but also can improve the efficiency of resource use.The research object of this paper is to study the spent RK-05 methanol synthesis catalyst of Ningxia Baofeng energy group of methanol synthesis in synthetic tower. With the dry wet combination method, the process of recovery of zinc oxide and copper oxide from spent RK-05 methanol synthesis catalyst is explored. At first, the spent catalyst should be crushed, grounded and baked; Then the catalyst after baking is leached with ammonium chloride solution, separating filtrate and filter residue, adjusting the pH of the filtrate, zinc hydroxide precipitation is prepared by the zinc ammonia complex ion hydrolysis and zinc oxide is obtained after filtration, drying, baking steps; Finally, crude copper powder is prepared by the replacement reaction with zinc particles put into the solution that composes of leaching residue and hydrochloric acid. At the same time, in the recovery process, the leaching solution of ammonium chloride can be recycled.The best process conditions were obtained by optimizing the experimental program:Size of catalyst powder:100 mesh, Bake temperature:950℃, Bake time:60 min. The optimum extraction conditions:Complex agent amount:300% of the theoretic value, Immerse temperature:75℃, Immerse concentration:4 mol/L, Immerse time:10 min. The optimal process conditions of product purification: the feeding ratio of the filter slag and zinc was 1:1; the optimal reaction time was 3 h; The optimum bake temperature of copper oxide was 450℃, and the optimum bake time of copper oxide was 4 h; The best bake temperature of Zinc Oxide was 800℃, and the optimum bake time of Zinc Oxide was 60 min.Using the recovery process, oxidation of copper recovery rate could reach up to 93.6%, product quality can meet GB/T674-2003 the copper oxide (indirect method), top-grade product standard; Zinc Oxide’s recovery rate can reach 90.3%, the product quality is able to meet the GB/T3185-92, Zinc Oxide (indirect method), first class standard requirement.