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Kansas Geological Survey, Bulletin 194, pt. 1, originally published in 1969

Attrition Scrubbing and Flotation Beneficiation of Cheyenne Sandstone (Lower Cretaceous, Kansas)

by Maynard P. Bauleke and Allison L. Hornbaker

Cover of the book; beige paper with black text.

Originally published in 1969 as part of "Short Papers on Research in 1968," Kansas Geological Survey Bulletin 194, part 1, p. 13-14. This is, in general, the original text as published. The information has not been updated.


Acidic attrition scrubbing reduced the iron oxide (Fe2O3) content of Cheyenne Sandstone to less than 0.040 percent. No significant improvement was obtained by an additional flotation treatment. Sand usage appears limited to foundry sand, abrasive sand, and low-quality glass sand.

The Cheyenne sandstone was sampled on the E. D. Robbins G lease in the E NW NW SW sec. 34, T. 30 S., R. 16 W., Kiowa County, Kansas (Fig. 1). The exposure is a nearly vertical section of Cheyenne Sandstone on the west bank in the bend of a small stream.

Figure 1--Location of sampling area of the Cheyenne Sandstone.

Map of a part of Kiowa and Barber counties; sampling area in SW Kiowa Co.

Channel samples were taken in order to obtain representative samples of the total sandstone section. For convenience in sampling, three channel cuts were taken en echelon up the face of the exposure--one for the lowermost 8 feet of section, the middle 6 feet, and the upper 8 feet, a total of 22 feet.

The sample of Cheyenne sandstone is composed essentially of generally rounded grains of sand. The heavy mineral concentrate consists of discrete grains of iron oxide, ilmenite, and zircon. Limonite associated with the sand grains appears to account for a large part of the total iron and is present in sufficient quantity to give the sand a slightly yellow color. Numerous sand grains contain inclusions of dark minerals. Occasional aggregates of sand grains cemented with limonite are present.

A partial chemical analysis (all chemical analyses done by the Geochemistry Laboratory, State Geological Survey of Kansas) on the "as dug" sample showed an iron oxide (Fe2O3) content of 0.092 percent, and an aluminum oxide (Al2O3) content of 0.89 percent. Particle size analysis of the sandstone is shown in Table 1. (All beneficiation tests done by the Denver Equipment Company, Ore Testing Division, Denver, Colorado.)

Table 1--Standard screen particle size analysis.

Screen mesh Percent weight on
screen mesh
Percent weight
20 0.5 0.5
28 1.0 1.5
35 4.0 5.5
48 21.5 27.0
65 36.0 63.0
100 25.5 88.5
200 11.0 99.5
-200 0.5  
  Total 100.0  

Seven attrition scrubbing tests were done (Table 2). A standard Denver Attrition Scrubber employing double-opposed-pitch propellers was used. Attrition scrubbing cleaned by abrading the sand particles with each other, rubbing away surface layers of iron minerals and clay. The scrubbed sand was deslimed by decantation through a 200-mesh screen.

Table 2--Results of attrition scrubbing tests.

Test: 1 2 3 4 5 6 7
Scrubber feed-percent solids 75.7 75.7 74.6 74.6 75.7 75.7 75.7
Reagents* N N OH OH H H N
Reagent dosage, lbs/ton     0.67 0.67 0.67 0.67  
Scrubbing stages 1 1 1 1 1 1 2
Scrubbing time, minutes 5 10 5 10 5 10 5;5
Pulp pH 7.6 7.6 11.5 11.5 2.5 2.5 7.6
Sand recovery, percent wgt 97.0 97.1 96.9 97.0 97.1 97.1 96.9
Slime recovery, percent wgt 3.0 2.9 3.1 3.0 2.9 2.9 3.1
Assay-sand: percent Fe2O3 0.057 0.037 0.045 0.035 0.040 0.029 0.034
Assay-sand: percent Al2O3 0.15 0.15 0.15 0.15 0.15 0.15 0.13
Approximate costs of chemicals,
cents per ton (f.o.b.)
    6.0 6.0 2.0 2.0  
N = None; OH = Sodium hydroxide; H = Sulfuric acid.

Four additional tests using both attrition scrubbing and flotation were run:

Test No. 8. After two stages of scrubbing, the sand was subjected to flotation using fatty acid collectors in an alkaline circuit to remove iron impurities as a froth product.

Flotation reagents lbs/ton sand
Sodium carbonate 0.40
Aero Promoter 710 0.55
Aero Promoter 765 0.65
Aerofroth 65 0.09

Iron content (Fe2O3) of the sand remaining in the cell was 0.028 percent. Total cost (costs listed are only approximations of current price fluctuations) of reagents was 21 cents per ton of sand recovered. Recovery was 95 percent.

Test No. 9. Scrubbing procedure was the same as for Test 8. Following scrubbing, the sand was conditioned with petroleum sulfonates in an acid circuit followed by flotation of the iron impurities in an acid circuit.

Flotation reagents lbs/ton sand
Sulfuric acid 0.67
Aero Promoter 801 0.40
Aero Promoter 825 0.40
No. 2 fuel oil 0.05
Aerofroth 65 0.20

Iron content (Fe2O3) of the sand remaining in the cell was 0.028 percent. Total cost of reagents was 19 cents per ton of sand recovered. Recovery was 95 percent.

Test No. 10. Scrubbing procedure was the same as Test 8. After scrubbing, the sand was floated away from the suspension by amine type collectors at a neutral pH. Flotation reagents were added in two stage additions to give two sand flotation concentrates and a final tailing.

Flotation reagents lbs/ton sand
Stage 1 Stage 2
Armac C 0.04 0.03
Methyl isobutyl carbinol 0.10 0.05

Iron content (Fe2O3) of sand collected during stage 1 was 0.028 percent, during stage 2, 0.030 percent. Total cost of reagents was 8 cents per ton of sand recovered. Recovery was 77 percent.

Test No. 11. As a last attempt to produce sand with a low iron content, a combination of scrubbing, impurity flotation, and sand flotation was tried. Chemical types and quantities were the same as in tests 8, 9, and 10. After a two-stage flotation of impurities, the sand was given a three-stage flotation to remove pure sand. The first stage of sand flotation gave the lowest iron content sand, 0.021 percent Fe2O3. However, the yield was only 26 percent of total sand. Treatment cost was $1.15 per ton of yield, a prohibitive cost for glass sand. The other two flotation stages gave sand with an iron content of 0.027 percent Fe2O3.

Enough of the iron content of Cheyenne sandstone is within the sand grain so that it is not possible by low-cost beneficiation methods to routinely produce a glass sand having an Fe2O3 content of less than 0.030 percent. Flotation gave no better product than did acid attrition. The extra cost of flotation is not justifiable.

For the area of Cheyenne sandstone sampled it appears that an iron content of 0.040 percent Fe2O3 or less could be routinely produced by low cost attrition beneficiation. Such sand could be used as foundry molding sand, sand blasting grit, and as glass sand where a slightly green color is not objectionable.

Kansas Geological Survey, Short Papers on Research in 1968
Placed on web July 26, 2011; originally published in Feb. 1969.
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