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LIST
OF CONTENTS
Introduction
Process Description
Typical
Contactor
Design
Criteria
Photos, Plans & Specs
Treatment
Performance
Operational
Skills
Automation
Potential
Advantages
Limitations
& Concerns
Pilot
Plant Objectives
Costs
References
Contacts & Facilities
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PROCESS DESCRIPTION
- CONTINUED
2. Physical and Chemical Properties of Limestone:
2.1. Limestone content:
There are several types of minerals that can be considered
as limestone and used as a media in a contactor. These include
marbles, calcite (CaCO3) and dolomite
(CaMg(CO3)2).
In Germany, half-burnt dolomite (CaCO3.MgO)
and porous calcium carbonate (CaCO3)
are used (Stauder, 2003). According to Letterman (1995), media
with the highest calcite and lowest dolomite content has the
highest initial rates of dissolution. When dolomite was used,
he found that the calcium carbonate component of the dolomite
dissolved faster than the magnesium carbonate component. A
similar result was reported by Plummer and Busenberg (1982)
(Letterman, 1995). Laboratory tests conducted by Menendez
et. al. (2000) using limestone to neutralize acidic mine drainage
also showed that the higher the CaCO3
content in the stone, the higher the dissolution rate. The
same result was also obtained in a study conducted by Letterman
(1995) where the overall dissolution rate constant decreased
by approximately 60% as the calcite content decreased from
0.92 to 0.09 g CaCO3 per gram stone.
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