SOLUBILISATION OF CARBONATES BY RECYCLING CONDENSATES ON DIGESTION UNDER PRESSURE OF MONOHYDRATE BAUXITES

摘要

The invention relates to a method for the production of aluminium from bauxites containing aluminium monohydate of the diaspore or boehmite type which may contain more than 1.5% by weight of calcium carbonates, the digestion of the ore comprising the following steps: a1) a suspension, produced from the milled bauxite ore and the concentrated aluminate liquor is fed to a plant comprising a series of n autoclaves and a series of m regulators supplying m tubular reheaters across m autoclaves with steam, a2) the suspension firstly travels across the series of autoclaves, on exiting the last autoclave An, the digestion of the ore is practically complete and a3) the suspension then travels across the series of regulators, the condensation water Esb&gti/sb&gt from the steam Vsb&gti/sb&gt coming from the regulator Dsb&gti/sb&gt and feeding the reheater Rsb&gtk/sb&gt is collected in a purge pot Psb&gtk /sb&gt. The method is characterised in that in at least one position in the series of regulators the suspension (Ssb&gti-1/sb&gt) is diluted on entering a regulator Dsb&gti/sb&gt with the water coming from the condensation of the steam from one or several upstream regulators.