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This document has not been fully peer reviewed and <strong>the</strong> <strong>information</strong> within is not validated nor endorsed by <strong>the</strong> TWG
on LVIC-S or by <strong>the</strong> European Commission, it is meant for <strong>information</strong>, only
The use of alternatives to aluminium hydroxide, like bauxite, will create a waste coming out of
<strong>the</strong> process mainly consisting of an insoluble silica rest. This is, however, less than when
bauxite is used for <strong>the</strong> production of aluminium hydroxide [50, CEFIC-INCOPA, 2004].
In <strong>the</strong> production of aluminium sulphate products containing iron, <strong>the</strong> iron ei<strong>the</strong>r comes directly
from <strong>the</strong> raw material (bauxite), or is separately added to <strong>the</strong> reactor, or is mixed with <strong>the</strong> final
product.
The process flow diagram of aluminium sulphate production is given in Figure 1.4.
8
Rest
Al (OH) 3
Liquid
production
Dilution
Filtration
Reaction
H 2 SO 4
Water
Solid
production
Crystallisation
Screening
Grinding
Storage Storage
Figure 1.4: Process flow diagram of aluminium sulphate production
[50, CEFIC-INCOPA, 2004]
Cooling
(water or air)
Dust to
process
Gas
cleaning
If air is used in direct contact with <strong>the</strong> product, <strong>the</strong> air is cleaned in a gas cleaning system. All
dust that is separated is returned to <strong>the</strong> process [50, CEFIC-INCOPA, 2004].
1.2.3 Current consumption and emission levels
1.2.3.1 Consumption of raw materials
Consumption figures for solid aluminium sulphate are about: 50 % sulphuric acid, 30 %
aluminium hydroxide, and 20 % water. The consumption figures for liquid products are about:
20 – 25 % sulphuric acid, 12 – 15 aluminium hydroxide and 60 – 65 % water. The reaction is
almost complete, <strong>the</strong> yield of <strong>the</strong> raw materials being nearly 100 % [50, CEFIC-INCOPA,
2004].
1.2.3.2 Major environmental impacts
Typical energy and water consumption figures and emissions values for liquid aluminium
sulphate are given in Table 1.5.