矿物加工专业英语

Magnezite Flotation(B)

Sodium silicate dissociates in aqueous solutions and then the silicate ion hydrolyses.An equilibrium diagram has been prepared to show the various products available in solution(Shergold,1982).In high concentrations，the silicate ion is polymerized to poly-silicic acid and colloidal silica, while dilution can produce depolymerisation (Marinakis,1980).Most of the silicate species are negatively charged .The nature of species and their concentration in a solution depend on the PH and concentration of initial solution，conditioning time and procedure of silicate addition .The action of this modifier can be due to one or more species .Adsorption of silicate on minerals was either physical or due to hydrogen bonds on suitable fluorite sites(Glembotskii et al .1972).

At frist,120 ppm of sodium silicate was tested on magnesite flotation by 20 ppm locate as a function of PH.The shape of the curve obtained was similar to the results with no modifier ,but silicate produced a slight activation (of about 45%).Increasing the collector concentration to 40 ppm did not change the situation ,while an increase concentration showed a small increase in magnesite recovery ,starting from 180 ppm of modifier.

As shown in Fig.7 with dolomite ,sodium silicate acted as a strong depressant at PH less than 9.0.This could be attributed to monosolicate ions which dominate in solutions in the 4.0-10.0.A comparison of the flotation behaviour of the teo minerals by 20 ppm of coliector,shown in Fig.8,gave an sppreciable ditiecontiation for 240 ppm of sodium silicate.