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Removal of Alkalies from Portland Cement Kiln Dust.

Authors
Wilson-RD; Anable-WE
Source
MISSING :10 pages
Link
NIOSHTIC No.
10005361
Abstract
Ten to twelve million tons of dust is produced by cement kilns annually in the United States, resulting in a serious waste disposal problem. The Bureau of Mines investigated two alkali volatilization methods for converting this dust into materials for making portland cement and a useful potassium product. Portland cement kiln dust was found to be composed of finely ground cement raw materials (caco3 and sio2) having a layer of alkali sulfate (k2so4 and na2so4). In this form, it cannot be directly recycled to cement kilns because concrete is weakened by a reaction between the alkali and the aggregate. Portland cements with 28-day strengths above 5,000 psi were produced from low-alkali residues using sintering and melting methods. For nearly complete removal of alkalies, primarily potassium sulfate, from cement kiln dust, a temperature above 1,300 deg. C and a reducing atmosphere were required.
Publication Date
19860101
Document Type
IH; Report of Investigations
Fiscal Year
1986
NTIS Accession No.
NTIS Price
Identifying No.
RI 9032
NIOSH Division
ALRC;
Source Name
MISSING
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