7
thickening devise for Allis-Chalmers, which unfortunately
did not prove to be successful. According to his son Bruce,
the senior Bond joked that the topic reflected the response
of his body to aging at the time. A pre-cursor to this work
was “Speeds Thickening Capacity Tests,” Engineering and
Mining Journal, January, 1940, in which he described a
method to shorten the time needed to conduct the usually
tedious thickening settling tests in graduated cylinders.
Bond’s discussion of ball wear as a function of ball size
in fine grinding was published in 1946 AIME Transactions.
He wrote that Allis-Chalmers laboratory experience was
that ball wear at low mill speeds is related to their surface
area (or diameter squared), but at high mill speeds is related
to their diameter to the power 2.29.
In 1947, Bond again updated tables of ball mill and
rod mill grindability tests, this time with the addition of
impact crushing tests. The same year he co-authored “Rod
Milling—Plant and Laboratory Data” with J.F. Meyers
of Tennessee Copper Co. (the leading author) and S.D.
Michaelson. In it they tabulated the operation of 25 indus-
trial rod mills and one roll crusher for which they also
conducted grindability testing on the feed. New surface
areas were calculated from mill feed to product using three
methods, as were reduction ratios based on Taggart’s (1943)
method of using the 80% passing (P80) sizes. Relative effi-
ciencies were calculated based on the comparative surface
areas of plant grinding versus that of the grindability test,
and also by the ratio of net product per kWh to grindability
at the same product size. The rolls crusher was considerably
most efficient. Many trends were noted, but aside from stat-
ing that rod mills were clearly more efficient on harder to
grind ores, conclusions were limited to the apparent lack of
consistent effect of many variables (for example mill speed,
diameter, and reduction ratio) on their grinding efficiency.
Lack of certain data (in particular rod charge level) was also
noted. They said Rittinger’s law was supported by the lesser
effect of variables on surface area efficiency than size pro-
duction efficiency, although the latter was more useful for
mill operators.
In a preprint prepared for the 1948 annual AIME con-
vention, Bond reported on “Ball Segregation in Grinding
Mills.” A series of tests in laboratory mills showed that spi-
ral liners and tapered mill shells have a similar effect on ball
segregation, that is the migration of larger balls towards the
feed end of the mill.
Bond had been promoted from Metallurgist, Mining
Department, to Head, Processing Development Laboratory,
to Director, Basic Industries Research Laboratory (report-
ing to the Manager of same) in 1944. That year they also
moved into a larger, newly constructed processing research
facility. But in his own words, “It became clear to me that I
was not a good manager, administrator or executive. I was
not good at delegating.” In 1950, one of his staff mem-
ber’s technical errors led to loss of an equipment order,
culminating in Bond’s demotion to “Consultant” and his
replacement by Will Mitchell. He called his staff of about
twenty together and told them “You are being released from
Bondage.” His technical capabilities were never in ques-
tion, however, either by Bond himself or Allis-Chalmers
management. And while personally financially respon-
sible, Bond was similarly somewhat unaware of econom-
ics. When driving through small towns apparently devoid
of industry, going from Milwaukee to Denver on vacation,
he commented “They must do each other’s laundry.” (B.
Bond, 2012)
In 1950, Bond’s discussion of a paper on “The Effect of
Mill Speeds on Operating Costs,” by H. Hardinge and R.C.
Ferguson, was published. He supported low ball mill speeds
(50–55% of critical), particularly for overflow (versus grate)
discharge mills, from an operating cost perspective.
Bond co-wrote “A New Theory of Comminution”
with Jen-Tung Wang in 1950. Wang was noted in the
author descriptions to be “Professor of Machine Design,
Chekiang University, China on leave of absence at Allis-
Chalmers Manufacturing Co., Milwaukee, Wis.” Wang
analyzed energy usage of a broad range of crushing and
grinding machines and graphically presented an approxi-
mate, empirical relationship with particle feed and prod-
uct sizing for a range of ores. The sizes were represented by
Taggart’s (1943 AIME paper and 1945 Handbook) eighty
percent cumulative passing sizes. Specific energy usage
in HP-h/t “is equal to one half of the square root of the
term reduction ratio to the one-half power, divided by the
product size in inches,” and “hp-hr per ton =Ki x (n^0.5/
P8 0)0.5, where Ki =0.5 on average (medium hardness)
materials, 0.25 for soft, and 1.0 for hard materials.” The
relationship HP-hr per ton versus the square root of reduc-
tion ratio divided by P80 (n^0.5/P80) plotted (with sub-
stantial scatter) as a straight line on a log-log scale. They
termed it “the strain energy theory,” and demonstrated
that it compromised between the Rittinger (new surface
area) and Kick (reduction ratio) theories. Until now, Bond,
and others at Allis-Chalmers, had generally expressed sup-
port of Rittinger’s theory, although troubled by the inabil-
ity to measure surface area of extremely fine particles and
its impracticality with regard to the plant product sizing
needed for mineral separation purposes. They also admitted
that it was inadequate in that it does not cover variations
in operating efficiencies of equipment reducing large and
small particles. And they hinted it may ultimately lead to an
thickening devise for Allis-Chalmers, which unfortunately
did not prove to be successful. According to his son Bruce,
the senior Bond joked that the topic reflected the response
of his body to aging at the time. A pre-cursor to this work
was “Speeds Thickening Capacity Tests,” Engineering and
Mining Journal, January, 1940, in which he described a
method to shorten the time needed to conduct the usually
tedious thickening settling tests in graduated cylinders.
Bond’s discussion of ball wear as a function of ball size
in fine grinding was published in 1946 AIME Transactions.
He wrote that Allis-Chalmers laboratory experience was
that ball wear at low mill speeds is related to their surface
area (or diameter squared), but at high mill speeds is related
to their diameter to the power 2.29.
In 1947, Bond again updated tables of ball mill and
rod mill grindability tests, this time with the addition of
impact crushing tests. The same year he co-authored “Rod
Milling—Plant and Laboratory Data” with J.F. Meyers
of Tennessee Copper Co. (the leading author) and S.D.
Michaelson. In it they tabulated the operation of 25 indus-
trial rod mills and one roll crusher for which they also
conducted grindability testing on the feed. New surface
areas were calculated from mill feed to product using three
methods, as were reduction ratios based on Taggart’s (1943)
method of using the 80% passing (P80) sizes. Relative effi-
ciencies were calculated based on the comparative surface
areas of plant grinding versus that of the grindability test,
and also by the ratio of net product per kWh to grindability
at the same product size. The rolls crusher was considerably
most efficient. Many trends were noted, but aside from stat-
ing that rod mills were clearly more efficient on harder to
grind ores, conclusions were limited to the apparent lack of
consistent effect of many variables (for example mill speed,
diameter, and reduction ratio) on their grinding efficiency.
Lack of certain data (in particular rod charge level) was also
noted. They said Rittinger’s law was supported by the lesser
effect of variables on surface area efficiency than size pro-
duction efficiency, although the latter was more useful for
mill operators.
In a preprint prepared for the 1948 annual AIME con-
vention, Bond reported on “Ball Segregation in Grinding
Mills.” A series of tests in laboratory mills showed that spi-
ral liners and tapered mill shells have a similar effect on ball
segregation, that is the migration of larger balls towards the
feed end of the mill.
Bond had been promoted from Metallurgist, Mining
Department, to Head, Processing Development Laboratory,
to Director, Basic Industries Research Laboratory (report-
ing to the Manager of same) in 1944. That year they also
moved into a larger, newly constructed processing research
facility. But in his own words, “It became clear to me that I
was not a good manager, administrator or executive. I was
not good at delegating.” In 1950, one of his staff mem-
ber’s technical errors led to loss of an equipment order,
culminating in Bond’s demotion to “Consultant” and his
replacement by Will Mitchell. He called his staff of about
twenty together and told them “You are being released from
Bondage.” His technical capabilities were never in ques-
tion, however, either by Bond himself or Allis-Chalmers
management. And while personally financially respon-
sible, Bond was similarly somewhat unaware of econom-
ics. When driving through small towns apparently devoid
of industry, going from Milwaukee to Denver on vacation,
he commented “They must do each other’s laundry.” (B.
Bond, 2012)
In 1950, Bond’s discussion of a paper on “The Effect of
Mill Speeds on Operating Costs,” by H. Hardinge and R.C.
Ferguson, was published. He supported low ball mill speeds
(50–55% of critical), particularly for overflow (versus grate)
discharge mills, from an operating cost perspective.
Bond co-wrote “A New Theory of Comminution”
with Jen-Tung Wang in 1950. Wang was noted in the
author descriptions to be “Professor of Machine Design,
Chekiang University, China on leave of absence at Allis-
Chalmers Manufacturing Co., Milwaukee, Wis.” Wang
analyzed energy usage of a broad range of crushing and
grinding machines and graphically presented an approxi-
mate, empirical relationship with particle feed and prod-
uct sizing for a range of ores. The sizes were represented by
Taggart’s (1943 AIME paper and 1945 Handbook) eighty
percent cumulative passing sizes. Specific energy usage
in HP-h/t “is equal to one half of the square root of the
term reduction ratio to the one-half power, divided by the
product size in inches,” and “hp-hr per ton =Ki x (n^0.5/
P8 0)0.5, where Ki =0.5 on average (medium hardness)
materials, 0.25 for soft, and 1.0 for hard materials.” The
relationship HP-hr per ton versus the square root of reduc-
tion ratio divided by P80 (n^0.5/P80) plotted (with sub-
stantial scatter) as a straight line on a log-log scale. They
termed it “the strain energy theory,” and demonstrated
that it compromised between the Rittinger (new surface
area) and Kick (reduction ratio) theories. Until now, Bond,
and others at Allis-Chalmers, had generally expressed sup-
port of Rittinger’s theory, although troubled by the inabil-
ity to measure surface area of extremely fine particles and
its impracticality with regard to the plant product sizing
needed for mineral separation purposes. They also admitted
that it was inadequate in that it does not cover variations
in operating efficiencies of equipment reducing large and
small particles. And they hinted it may ultimately lead to an