You are here:
CALCIUM CARBONATE DISSOLUTION RATE IN LIMESTONE CONTACTORS
Citation:
Letterman, R. D. CALCIUM CARBONATE DISSOLUTION RATE IN LIMESTONE CONTACTORS. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-95/068 (NTIS PB95-222733), 1995.
Impact/Purpose:
Information
Description:
The rate of carbonate mineral dissolution from limestone was studied using a rotating disk apparatus and samples of limestone of varied composition. The purpose of this study was to determine the effect of limestone composition on the kinetics of carbonate mineral dissolution. The results are needed to improve the relationships used to design limestone contactors for long term operation.
The stone samples with the highest calcite content and lowest dolomite content had the highest initial rates of dissolution. The magnitude of the overall dissolution rate constant for fresh stone decreased by approximately 60% as the calcite content of the stone decreased from 0.92 to 0.09 g CaCO3/g stone.
The overall dissolution rate constant decreased as the amount of calcium dissolved from the surface of the stone increased. Analysis of several stone surfaces indicated that a residue layer of aluminum, silicon and iron formed as calcium dissolved.
For a given amount of calcium dissolved per unit area of stone surface, the magnitude of the decrease in the dissolution rate constant increased as the initial amount of iron and aluminum in the stone increased. The results suggest that the effect of sample aging on the rate of dissolution is at a minimum if the weighted sum of the Fe and Al content of the stone is less than about 10 mg/g. The weighted sum is equal to the aluminum content in mg Al/g plus 0.30 times the iron content in mg Fe/g.
This report was submitted in fulfillment of CR814926 by Syracuse University under the sponsorship of the U.S. Environmental Protection Agency. This report covers a period from July 1988 to June 1993 and work was completed as of June 30, 1993.