US 4,401,638 AGranted

Process for purifying silica sand

AssigneeMaterias Primas, Monterrey, S.A.

InventorsAlejandro J. Caballero, Ricardo I. Holcombe

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Abstract

A process of purifying silica sand comprises grinding sandstone, washing and desliming the ground sandstone to remove the major part of the clay-type binder, attrition-scrubbing the deslimed sand particles to release further amounts of binder therefrom, washing and desliming to remove said binder, drying and heating the sand particles, treating the hot sand with sulfuric acid to convert the iron oxides, ferrosilicates and ferro-aluminous impurities into water soluble compounds, attrition-scrubbing the hot suspension of the chemically treated sand to release the strongly adhering stains of said impurities, washing with cold water and desliming, conditioning the sand suspension with fatty acids or petroleum sulfonate collectors, a polyalcohol frothing agent and, if necessary, a mineral acid to bring the pH to from 1.5 to 7.0, carrying out a first froth-flotation to remove the remaining ferrosilicates and iron oxides, and carrying out a second froth-flotation with a fatty amine collector in the presence of sulfuric acid and/or hydrofluoric acid to activate the aluminosilicates and to remove the same at a pH of from 1.5 to 3.5.

Claims8

Dependent claims

A process of purifying silica sand comprising:

a. grinding sandstone to obtain sand particles;
b. washing and desliming said particles to remove a major portion of clay-type binder contained in said sandstone;
c. attrition-scrubbing said deslimed sand particles to release further amounts of said binder from said particles;
d. further washing and desliming said sand thereby essentially removing said further amounts of said binder;
e. drying and heating said sand;
f. treating said hot sand particles with a solution of sulfuric acid to convert at least one of impurities selected from the group consisting of iron oxides, ferro-silicates and ferro-aluminous compounds into water soluble compounds;
g. attrition-scrubbing the resulting hot suspension of said acid treated sand particles to release strongly adhering stains of said impurities from said particles;
h. washing said suspension with cold water and desliming;
i. conditioning said suspension with collectors and frother;
j. floating and removing at least one of remaining ferrosilicates and iron oxides in a first flotation step conducted at a pH ranging from 1.5 to 7;
and
k. floating and removing remaining aluminosilicates in a second flotation step using a fatty amine collector in the presence of at least one activator selected from the group consisting of sulfuric acid and hydrofluoric acid.

9 more elements

Dependencies are inferred from the claim text.