Study On The Desilication Of Raw Liquid In Sintering Process Alumina Production

Three-stage desilication of raw liquor is adopted in sintering process alumina production in Shandong Aluminum Corporation. The energy consumption of the first stage is high because severs pipe scaring and difficult to clear. The second stage is processed without separating sodium-silicon residue. during the second stage sodium-silicon is re-dissolved into solution. Depth desilication uses lime milk as desilication reagent. A mass of desilication residues are returned to material preparation procedure. More seeds are needed and loads of equipment increase. Aiming at these unrationalities, new technologies are studied and brought forward. First, pre-desilication of raw liquor is carried out. Second, desilication seeds are added after simple activation. Third, in sodium-silicon residue separation procedure,叶滤机is substituted by settlement, and desilication process becomes simple. Last, desilication with adding HCAC after separating sodium-silicon residue and the third stage desilicatin is cancelled.In this paper, factors that influence normal-pressure desilication are studied. Seed activation is especially studied. So in practice, Activation is carried out through digesting seeds with vaporized spent liquor. High effective flocculant is adopted to reduce solid content of the pregnant liquor obtained from the first stage to improve the desilicatin effect of the second stage. And theory of affection of various factors on the second stage desilication is disclosed.In this paper, all raw materials are got from process. Through experiment in laboratory, technology conditions suitable for Shandong Aluminum Corporation are gained and mentioned below:Pre-desilication of raw liquor:quantity of seeds:50-60g/L temperature:95℃±, time: 3 hours, A/S of desilicated liquor:150.The first stage desilication under high pressure:temperature:140-150℃, time:1 hour, A/S of the first stage refined liquor:300±, and solid content of the refined liquor is controlled blow 0.5g/L.The second stage desilication under air pressure:use HCAC as desilication reagent, quantity of added effective calcium oxide:6g/L, temperature:92-95℃, time:2 hours, A/S of the second stage refined liquor:800±.All calcium-silicon residue is used to recover alumina with carbon dioxide precipitated spent liquor or directly produce aluminum salt.Sodium-silicon residue is divided into two parts:one part returns to pre-desilication as seeds after activation, the other part is used to produce 4A zeolite.