PROCESS FOR PRODUCING AGGLOMERATES FROM DUSTS

摘要

A process for producing strong, essentially dust-free agglomerates from dust created by an industrial operation carried out, for example, on an ore or mineral, e.g. during the thermal conversion of a material containing predominantly gibbsite to sub-alpha alumina by a multistage thermal process having at least one intermediate stage. The process comprises grinding particles of binder material containing undercalcined alumina to a median particle size of less than 30 x 10<-4> cm (30 microns) and to a specific surface area in the range of 90-300 m<2>/g; combining about 1-4 parts by weight of the dust with one part by weight of the ground binder material to form combined solids; mixing the combined solids with water to produce agglomerates. The water is mixed with the combined solids by intensive mixing in a mixer equipped with a mixing motor, the water being added according to a two-step scheme in which: (a) 40-80 % of the total amount of water is added to the combined solids at a rate such that no more than 10 minutes are required for complete addition; (b) commencing the addition of the remainder of the water and measuring a characteristic of said mixture corresponding to its viscosity and using the measurement as a reference value; and (c) continuing the addition of the remainder of the water while continuing to measure the characteristic of the mixture, the water being added at such a rate that the characteristic of the mixture remains the same as the reference value during the addition or varies by less than +/- 5 %.