9
variables. It is clear that Bond was mainly focused on show-
ing the trends of square root of particle size versus energy
usage. He also states that “Comparisons of the relative effi-
ciencies of different plants can be made by dividing the
plant work index by the laboratory work index,” thus pro-
viding a definition of plant grinding efficiency for the first
time. Scale-up design of new installations is not specifically
mentioned, although it is implied, and “closer predictions,”
as well as “more accurate comparisons of all crushing and
grinding installations,” are noted in the closing paragraph.
Bond soon followed with mill selection calculations
(“New Grinding Theory Aids Equipment Selection) based
on work index in Chemical Engineering, October, 1952, and
a table of “Average Work Indexes” for fifty-eight materials
(“Work Indexes Tabulated,” Mining Engineering, March,
1953). He expanded these works into more complete trea-
ties on use of work index for rod and ball mill selections in
the following publications.
Bond originally presented “Mathematics of Crushing
and Grinding” to IMM in London in September, 1952,
and it was published by IMM as part of those conference
proceedings in Recent Developments in Mineral Processing.
He again starts by comparing his Third Theory with those
of Kick and Rittinger. Equations were given to derive work
index values from Allis-Chalmers crushability and rod and
ball mill grindability tests. The work index equation was
used to calculate kWh/t at each step. Mills were sized from
power draw per ton of grinding media, as Michealson had
in 1944. He thusly specifies two stages of crushing and
selects the rod mill and ball mill, completing the conven-
tional plant comminution circuit of the time. Rod and ball
mill media sizing was also included, along with equations
to estimate metal wear. He presented an updated variation,
“Crushing and Grinding Calculations,” to the CIMM in
April, 1954, and it was subsequently published later that
year in both CIM Bulletin and CIM Transactions. He pre-
sented the same at SME in Chicago, February, 1955, and
it was updated by Allis-Chalmers Press in 1956, 1961 and
finally again in 1962 replicating its publication in two
parts in British Chemical Engineering in June and August,
1961. Copyright privileges were apparently shared by Allis-
Chalmers, not signed over, throughout.
Meanwhile, in 1954, Bond compared the efficiency of
blasting to that of coarse crushing in “What is the More
Efficient Rock Breaker?” (E&MJ, Jan.) He used the work
index equation and some broad assumptions to suggest that
they are approximately equal in efficiency. Also in 1954, he
wrote of how to “Control Particle Shape and Size.” (Chemical
Engineering, Aug.). He defined shape factor by comparison
with an ideal ellipsoid. While he stated that material char-
acteristics dominate product particle state, he noted that
machines that break by impact versus abrasion produce
more cubical products. He described work index again in
the same article. Finally, the same year his comments on
“Some Grinding Tests with Spheres and Other Shapes,” by
C. Chad Norris, were published in the November Bulletin
of the Institution of Mining and Metallurgy. He used work
index calculations to conclude that “This paper is valuable
because it offers detailed proof that spherical grinding balls
are more efficient than any of the other five shapes of grind-
ing media tested.”
In January of 1955, Bond presented “The Role of the
Rod Mill in the Grinding Circuit” to a forum on crushing
and grinding hosted by the Canadian Institute of Mining
and Metallurgy. It described the development of Allis-
Chalmers rod mill power draw equation, and the applica-
tion of the Third Theory to rod mill size selection.
In 1955 Bond summarized his Third Theory in “How
Does Rock Break” for The Scientific Monthly. He noted
great inefficiency in that “Reduction is now accomplished
by undirected brute force,” and that “Some method of
obtaining comminution by a directed energy flow may rev-
olutionize the breaking of rock and result in a great saving
of power and steel.” This perhaps foretold a later move in
that direction by high-pressure grinding.
Bond compared “Wet versus Dry Grinding” at the
American Mining Congress in 1956, which was published
much later in German (Aufbereitungs-Technik nr. 3/1962).
He summarized advantages and disadvantages, concluding
Figure 4. Fred C. Bond, circa 1952
(courtesy of Bruce F. Bond)
variables. It is clear that Bond was mainly focused on show-
ing the trends of square root of particle size versus energy
usage. He also states that “Comparisons of the relative effi-
ciencies of different plants can be made by dividing the
plant work index by the laboratory work index,” thus pro-
viding a definition of plant grinding efficiency for the first
time. Scale-up design of new installations is not specifically
mentioned, although it is implied, and “closer predictions,”
as well as “more accurate comparisons of all crushing and
grinding installations,” are noted in the closing paragraph.
Bond soon followed with mill selection calculations
(“New Grinding Theory Aids Equipment Selection) based
on work index in Chemical Engineering, October, 1952, and
a table of “Average Work Indexes” for fifty-eight materials
(“Work Indexes Tabulated,” Mining Engineering, March,
1953). He expanded these works into more complete trea-
ties on use of work index for rod and ball mill selections in
the following publications.
Bond originally presented “Mathematics of Crushing
and Grinding” to IMM in London in September, 1952,
and it was published by IMM as part of those conference
proceedings in Recent Developments in Mineral Processing.
He again starts by comparing his Third Theory with those
of Kick and Rittinger. Equations were given to derive work
index values from Allis-Chalmers crushability and rod and
ball mill grindability tests. The work index equation was
used to calculate kWh/t at each step. Mills were sized from
power draw per ton of grinding media, as Michealson had
in 1944. He thusly specifies two stages of crushing and
selects the rod mill and ball mill, completing the conven-
tional plant comminution circuit of the time. Rod and ball
mill media sizing was also included, along with equations
to estimate metal wear. He presented an updated variation,
“Crushing and Grinding Calculations,” to the CIMM in
April, 1954, and it was subsequently published later that
year in both CIM Bulletin and CIM Transactions. He pre-
sented the same at SME in Chicago, February, 1955, and
it was updated by Allis-Chalmers Press in 1956, 1961 and
finally again in 1962 replicating its publication in two
parts in British Chemical Engineering in June and August,
1961. Copyright privileges were apparently shared by Allis-
Chalmers, not signed over, throughout.
Meanwhile, in 1954, Bond compared the efficiency of
blasting to that of coarse crushing in “What is the More
Efficient Rock Breaker?” (E&MJ, Jan.) He used the work
index equation and some broad assumptions to suggest that
they are approximately equal in efficiency. Also in 1954, he
wrote of how to “Control Particle Shape and Size.” (Chemical
Engineering, Aug.). He defined shape factor by comparison
with an ideal ellipsoid. While he stated that material char-
acteristics dominate product particle state, he noted that
machines that break by impact versus abrasion produce
more cubical products. He described work index again in
the same article. Finally, the same year his comments on
“Some Grinding Tests with Spheres and Other Shapes,” by
C. Chad Norris, were published in the November Bulletin
of the Institution of Mining and Metallurgy. He used work
index calculations to conclude that “This paper is valuable
because it offers detailed proof that spherical grinding balls
are more efficient than any of the other five shapes of grind-
ing media tested.”
In January of 1955, Bond presented “The Role of the
Rod Mill in the Grinding Circuit” to a forum on crushing
and grinding hosted by the Canadian Institute of Mining
and Metallurgy. It described the development of Allis-
Chalmers rod mill power draw equation, and the applica-
tion of the Third Theory to rod mill size selection.
In 1955 Bond summarized his Third Theory in “How
Does Rock Break” for The Scientific Monthly. He noted
great inefficiency in that “Reduction is now accomplished
by undirected brute force,” and that “Some method of
obtaining comminution by a directed energy flow may rev-
olutionize the breaking of rock and result in a great saving
of power and steel.” This perhaps foretold a later move in
that direction by high-pressure grinding.
Bond compared “Wet versus Dry Grinding” at the
American Mining Congress in 1956, which was published
much later in German (Aufbereitungs-Technik nr. 3/1962).
He summarized advantages and disadvantages, concluding
Figure 4. Fred C. Bond, circa 1952
(courtesy of Bruce F. Bond)