6
Building Science Abstracts (1942). Numerous materials were
lab ball mill tested and showed that most tended to result
in ball coating when ground finely enough, although a few
(glass, for example) did not. The possible mechanisms (elec-
trostatic, adsorption, mechanical) and the roles of moisture
and certain mixtures were discussed, along with the role of
grinding ball material. Small quantities of a lubricant (such
as coal) or a patented liquid reagent (containing lignin)
were shown to almost eliminate ball coating.
Bond’s 1941 paper on “Measuring Surface Area in
Grinding” provided a method for estimating total surface
area produced in grinding based on that of individual mesh
sizes, once again needed for demonstrating Rittinger’s law.
It required the existence of a “grind limit” below which fur-
ther breakage would not take place, an assumption which
was challenged by Prof. Schuhmann in subsequent pub-
lished discussion of the paper.
Bond followed with “Shape Factors of Comminution
Products.” Dimensions A, B and C were defined as the larg-
est dimension, largest dimension at right angles to A, and
largest dimension at right angles to B and C, respectively.
C is measured by screen analysis (square openings). He
compared five crusher products, noting how the “shape fac-
tor,” the deviation from an ideal ellipsoid, changes with size
reduction of different materials.
In 1942–43, Bond provided equations that could be
used in sand blending for Rock Products magazine. They pro-
vided the ratios of materials needed to be added or removed
in order to achieve a desired size distribution specification.
In 1943 Bond and Maxson updated the 1933 and
1938/39 tables of the ball mill grindability tests, and added
a table of eighty-five “standard rod-mill grindability tests.”
Rod-mill grindability tests were never previously men-
tioned, but had “become increasingly important,” appar-
ently with the growth of rod milling. No discussion was
provided of its development at Allis-Chalmers, which
presumably took place mainly since the previous 1938/39
publication. The test was described in detail, and used the
same equipment and procedure that is prescribed today.
In 1944 Stanley D. Michaelson solely (notably, almost
inexplicably, without Bond) published the paper on
“Determination of Ball Mill Size from Grindability Data.”
This revealed exactly how to select a ball mill for a new
operation based on a grindability test of the circuit feed. A
series of plant “standard operations” were studied to deter-
mine net (amount in the circuit product minus that in the
circuit feed) production (or grinding) rate of a given par-
ticle size per kilowatt-hour (for example, the net tons of
new minus 200 mesh size per kWh). Grindability tests were
performed on samples of the circuit feeds taken during the
plant studies so the net circuit production/grinding rates
could be compared to ball mill laboratory test grindabilities
on the same ore. A comparative (graphical) data base of
grindabilities of these ores at different grinds was created.
For a new circuit, the ore’s grindability at the same mesh
size would be compared to a higher and lower grindabil-
ity ore, and the new plant required kWh/t estimated from
those of the two “standard operations” by interpolation.
An adjustment could be made for known efficiency factors,
such as that for grate versus overflow discharge (providing
approximately 4% higher efficiency) and mill diameter
(not quantified by Michaelson). The kWh per ton times
the design tonnage provided the needed mill power. Mills
of appropriate diameter and length were then selected on
the basis of reference mills which provided power draw per
ton of grinding media.
Although referencing four of Bond and Maxson’s
jointly written papers, Michealson acknowledged only
“the staff of Allis-Chalmers Manufacturing Co., under the
direction of W.L. Maxson” at the end of the paper. As the
author he identified himself as Ore Dressing Engineer cur-
rently (Dec., 1944) serving as a Major in the U.S. army.
Michealson had joined A-C circa 1936 (a relative, nee
1913) newcomer, compared to Bond in 1930, and Maxson
previous to that), served in the army 1941–46, and left
Allis-Chalmers in 1947. He then worked for U.S. Steel and
Kennecott, advancing to Chief Engineer at both compa-
nies. He was active in the SME, for which he became presi-
dent in 1958.
Michaelson’s sole authorship is extremely odd. The
importance of the topic suggests high level clearance would
be needed. The work was not much of his doing. It was not
presented at any conference. He acknowledges the above
mentioned for “their review and approval of the subject
matter.” Does exclusion of others, and his later professional
success, suggest great ambition? He also references a paper
by himself, Wolf and Maxson “read at AIME in February,
1938,” but not written, on the effect of circulating load on
grindability test results (these are “rather minor,” they said,
over the range of 100% -1,000%).
In “Cushing Tests by Pressure and Impact” (1946),
Bond describes the development of impact crushing tests at
Allis-Chalmers, culminating in the twin pendulum crush-
ing tests still in use today. It is notable that they avoided
drop-weight methods on the grounds that an indetermin-
able portion of the energy is transmitted into the base.
In a complete change of topic, Bond wrote “Thickening
and Settling” (1946) describing fundamentals and test-
ing methods for the design of industrial thickeners. At
the time he was involved with the development of a new
Building Science Abstracts (1942). Numerous materials were
lab ball mill tested and showed that most tended to result
in ball coating when ground finely enough, although a few
(glass, for example) did not. The possible mechanisms (elec-
trostatic, adsorption, mechanical) and the roles of moisture
and certain mixtures were discussed, along with the role of
grinding ball material. Small quantities of a lubricant (such
as coal) or a patented liquid reagent (containing lignin)
were shown to almost eliminate ball coating.
Bond’s 1941 paper on “Measuring Surface Area in
Grinding” provided a method for estimating total surface
area produced in grinding based on that of individual mesh
sizes, once again needed for demonstrating Rittinger’s law.
It required the existence of a “grind limit” below which fur-
ther breakage would not take place, an assumption which
was challenged by Prof. Schuhmann in subsequent pub-
lished discussion of the paper.
Bond followed with “Shape Factors of Comminution
Products.” Dimensions A, B and C were defined as the larg-
est dimension, largest dimension at right angles to A, and
largest dimension at right angles to B and C, respectively.
C is measured by screen analysis (square openings). He
compared five crusher products, noting how the “shape fac-
tor,” the deviation from an ideal ellipsoid, changes with size
reduction of different materials.
In 1942–43, Bond provided equations that could be
used in sand blending for Rock Products magazine. They pro-
vided the ratios of materials needed to be added or removed
in order to achieve a desired size distribution specification.
In 1943 Bond and Maxson updated the 1933 and
1938/39 tables of the ball mill grindability tests, and added
a table of eighty-five “standard rod-mill grindability tests.”
Rod-mill grindability tests were never previously men-
tioned, but had “become increasingly important,” appar-
ently with the growth of rod milling. No discussion was
provided of its development at Allis-Chalmers, which
presumably took place mainly since the previous 1938/39
publication. The test was described in detail, and used the
same equipment and procedure that is prescribed today.
In 1944 Stanley D. Michaelson solely (notably, almost
inexplicably, without Bond) published the paper on
“Determination of Ball Mill Size from Grindability Data.”
This revealed exactly how to select a ball mill for a new
operation based on a grindability test of the circuit feed. A
series of plant “standard operations” were studied to deter-
mine net (amount in the circuit product minus that in the
circuit feed) production (or grinding) rate of a given par-
ticle size per kilowatt-hour (for example, the net tons of
new minus 200 mesh size per kWh). Grindability tests were
performed on samples of the circuit feeds taken during the
plant studies so the net circuit production/grinding rates
could be compared to ball mill laboratory test grindabilities
on the same ore. A comparative (graphical) data base of
grindabilities of these ores at different grinds was created.
For a new circuit, the ore’s grindability at the same mesh
size would be compared to a higher and lower grindabil-
ity ore, and the new plant required kWh/t estimated from
those of the two “standard operations” by interpolation.
An adjustment could be made for known efficiency factors,
such as that for grate versus overflow discharge (providing
approximately 4% higher efficiency) and mill diameter
(not quantified by Michaelson). The kWh per ton times
the design tonnage provided the needed mill power. Mills
of appropriate diameter and length were then selected on
the basis of reference mills which provided power draw per
ton of grinding media.
Although referencing four of Bond and Maxson’s
jointly written papers, Michealson acknowledged only
“the staff of Allis-Chalmers Manufacturing Co., under the
direction of W.L. Maxson” at the end of the paper. As the
author he identified himself as Ore Dressing Engineer cur-
rently (Dec., 1944) serving as a Major in the U.S. army.
Michealson had joined A-C circa 1936 (a relative, nee
1913) newcomer, compared to Bond in 1930, and Maxson
previous to that), served in the army 1941–46, and left
Allis-Chalmers in 1947. He then worked for U.S. Steel and
Kennecott, advancing to Chief Engineer at both compa-
nies. He was active in the SME, for which he became presi-
dent in 1958.
Michaelson’s sole authorship is extremely odd. The
importance of the topic suggests high level clearance would
be needed. The work was not much of his doing. It was not
presented at any conference. He acknowledges the above
mentioned for “their review and approval of the subject
matter.” Does exclusion of others, and his later professional
success, suggest great ambition? He also references a paper
by himself, Wolf and Maxson “read at AIME in February,
1938,” but not written, on the effect of circulating load on
grindability test results (these are “rather minor,” they said,
over the range of 100% -1,000%).
In “Cushing Tests by Pressure and Impact” (1946),
Bond describes the development of impact crushing tests at
Allis-Chalmers, culminating in the twin pendulum crush-
ing tests still in use today. It is notable that they avoided
drop-weight methods on the grounds that an indetermin-
able portion of the energy is transmitted into the base.
In a complete change of topic, Bond wrote “Thickening
and Settling” (1946) describing fundamentals and test-
ing methods for the design of industrial thickeners. At
the time he was involved with the development of a new