THE PATH OF TECHNOLOGY — Хонинговальные головки

Over the centuries, great technical achievements led to the machines of today, which can grind solid particles at the rate of tens of thousands of tons per day. The evolution of machines from devices driven by one person to immense machines with capacities of many hundred tons per hour driven by motors larger than 20,000 kW (27,000 hp) has followed the path of technology in general, encapsulated by Henry Hodges (1970) in the final chapter of his book entitled Technology in the Ancient World:

Nowhere was the rate of technological advance a steady, even, upward climb.

Always one seems to be confronted with sudden bursts of technological innovation followed by long periods of virtual stagnation.

and

If the history of technology in the ancient world is to teach us anything at all it is to tell us that no technology can stand long on its own in glorious isolation. For a technology to thrive and develop required the presence of other often quite unrelated technologies alongside it from which ideas could be lent or borrowed. Such was the case, anyway, in the ancient world. One is left wondering whether the world of today is so very different.

TABLE 1.3 Energy consumed in grinding some widely used products

Material	Energy Used, kW-hr/t
Hard coal in power plants	7.6
Cement	67.5
Iron ore	40
Nonferrous ore	~30
Phosphate ore	~40
Inorganic pigment	880
Organic pigment	220
Wood pulp cellulose	1500
Cereals	26.5
Sugar, cacao, dried milk	45
Burnt lime	15

Source: Rumpf 1977.

THE CONTRIBUTION OF TECHNICAL AND NONTECHNICAL FACTORS

Key Technical Factors

■ Processes were developed late in the 19th and early in the 20th centuries for producing cement and metals. These techniques—the McArthur-Forrest process (invented by J. S. McArthur and R. and W. Forrest) for leaching fine-grained gold ores, the flotation process for concentrating sulfides in fine-grained metal ores, and the rotary kiln for making cement—required finer particles than the mills at the time could produce. The ball mills built for these processes eventually grew into the huge machines of the 21st century.

■ Electrical and mechanical engineering improvements allowed compact, high-power motors to be built and produce power to be transmitted efficiently into mill drives.

■ High-quality steels that were resistant to wear, impact, and fatigue were invented; these reduced equipment breakdowns and increased production rates.

■ Scientific advances led to better equipment and techniques for design and control.

Key Nontechnical Factors

■ When the economic regime that controlled taxation and the availability of capital and skilled labor was favorable, owners of plants in which grinding mills were used invested in new equipment, including new sources of energy and materials.

■ A vibrant mood of intellectual inquiry, which had been evident during the prosperous years of the Greek and Roman empires, the Renaissance, and the Science Age in the 19th century, emerged again during the second half of the 20th century, leading to much progress in size-reduction technology in Europe and the United States.

Karl Marx had no doubt about the importance of the grinding mill to the history of mechanical technology itself: “…the history of the development of machines may be retraced by the history of the flour mill” (Kuprits 1967).

As we review the history of size reduction, we should keep in mind that both technical and nontechnical factors came into play in the technology’s evolution, particularly in the 20th century (see sidebar). In the rest of this chapter we review how sources of energy, quality of materials, and investments in technology changed the practice of size reduction (see Table 1.4 and Figure 1.2).

8 \| THE HISTORY OF GRINDING
TABLE 1.4 The progress of size-reduction technology*
Stages in Technology Development	Factors Interacting at Each Stage
Human muscles Men or animals working together Waterpower Steam power Electricity	Available materials Accumulated skills and experience Economic and social conditions Religious and ethical tenets Philosophical doctrines
Energy Available per Machine	Power Delivered by Muscles, ft-lb/sec
Stone Age—Human muscles: 0.1 kWt/person 600 BC—Men or animals working together: 0.5 kW 100 BC—Water wheel: 5 kW* 1800—Steam engine: up to 50 kW§ 1900—Electricity: 30,000+ kW (no limit)	Draft horse: 432 Ox: 288 Mule: 216 Donkey: 108 Human pumping: 33 Human winching: 45

Source: Adapted from Forbes 1955.

* We do not include explosive energy in the table because its growth has been separate from the growth of mechanical size reduction; however, explosives have been crucially important in size reduction, and the same interacting factors apply.

t 1 hp (0.746 kW) = 500 ft-lb/sec.

* Large water wheels generated more than 50 kW, but 5 kW seems a reasonable estimate for power used by many grinding machines operated by waterpower.

§ 50 kW is a reasonable estimate for steam engines used to drive grinding machines.

Energy

Electricity

Muscles Water

Steam

Age

Century

FIGURE 1.2 Effects of energy sources and materials on size-reduction processes

THE PATH OF TECHNOLOGY

Table 1.5 gives a brief chronology of size-reduction technology, and Table 1.6 presents a more detailed chronology. (Italics denote an event that contributed to substantial progress in size-reduction technology.)

TABLE 1.5 Brief chronology of the development of energy used for size-reduction technologies

Time Frame	Technology	Effects
Muscle Power
Stone Age	Mortars and pestles	Pounding action; good for coarse grinding
2000 BC	Saddlestones	Reciprocating action; good for fine grinding
500 BC	Querns	Rotary action; good for grinding soft grains, less satisfactory for grinding hard ores
Waterpower
1500 AD	Stamp mills driven by water wheels	Pounding action; good coarse-grinding machine
Steam Power
1850-1900	Jaw crushers, ball mills, air classifiers	High-capacity machines for ores and cement
	Roller mills for grains	Precise machines to grind grains incrementally
Electricity
1900-1920	Vertical roller mills, rake classifiers,	Closed grinding circuits for ores, coal, and
	autogenous pebble mills	cement; stones used as grinding media
1930-1955	Primary autogenous mills	Rocks or ore used as grinding media
1960-1975	High-diameter, short-length	Eliminated crushers in iron and copper ore
	semiautogenous mills	circuits
1985-1999	Large tumbling mills, high-speed stirred mills	Very high-capacity and very fine-grinding machines

TABLE 1.6 Full chronology of size-reduction technology

Source of Power	Time Frame*	Machines and Processes
Muscle Power
People	Stone Age	Mortars and pestles; hand stones; rock masses broken by fire and stone hammers
	2500 BC	Hand-operated bellows for compressed air
	2000 BC	Saddlestone mills
	1500 BC	Foot-operated bellows for compressed air
	500 BC	Rotary querns
Cattle	200 BC	Rotary querns
Water Wheels and Windmills
Horizontal wheel	100 BC	Water-driven rotary querns, initially in east Mediterranean
Vertical wheel	20 AD	Water-driven rotary querns, initially in Roman Empire
Windmill	700	Wind-driven rotary querns, initially in Persia, Afghanistan
	200	Edge roller mills in China for fine grinding
Vertical water wheel	400	Waterpower replaced muscle power for grain milling in Roman Empire
	800	Dry stamp mills (manual power)
	1320	Black powder used for military purposes
	1512	Water-driven wet stamp mills
	1546	De Re Metallica: Agricola’s textbook on mining engineering

TABLE 1.6 Full chronology of size-reduction technology (continued)

Source of Power Time Frame*

Machines and Processes

1558

1587

1589

1627

1776

1785

Corrugated roller mill for grains—not used for 300 years Amalgamation process for silver extraction Arrastra for grinding and mixing in amalgamation process Black powder used for mining purposes Mechanical air compressor Oliver Evans’ automatic flour mill Steam

Steam engines 1800 1827 1831

Cornish roll crushers invented to grind ores in Cornwall, England Portland cement produced

Bickford miners’ safety fuse invented for blasting with black powder in Cornwall

1838

1839

1840

1847

1848

1849

1847 1858 1860 1867 1867 1867 1870

1870

1870 1876 1880

Singer steam churn drill

Iron roller mills for grinding grains

Patent for hammer mill

Nitroglycerin introduced as first high-energy explosive William Easby’s high-pressure, double-roll compactor Mechanical percussion drill

Fine sieves and aspirators for flour sifting and purification

Eli Blake jaw crusher

Rock drill powered by compressed air

Dynamite made from nitroglycerin

Fulminate of mercury blasting cap invented for nitroglycerin Peter von Rittinger’s energy-size reduction theory (first theory) Rotary kiln to produce cement clinker Alsing batch ball mill for grinding flint for potteries Tripod-mounted rock drills

Gebruder Sachsenberg’s screen-discharge ball mill Corrugated iron rolls used for grain milling, leading to gradual reduction system

1881

1885

1888

1889

1891

1895

1898

Philetus Gates’ gyratory crusher Askham dry air separator

Friedrich Kick’s energy-size reduction theory (second theory) Vertical roller mill (F. E. Huntington’s mill)

Cyanide process for gold extraction First patent on hydrocyclones

Electric delay blasting caps invented by H. Julius Smith Thomas Edison’s giant rolls Water-flushed hammer drills

Ball mills used to grind gold ores in South Africa, Australia Medium-speed pin mill Electricity

Electrical motors 1900

1904

1905

1906

1904 1909

Vertical ring-roller and ring-ball mills for coal and soft ores J. V.N. Dorr’s mechanical hydraulic classifier Flotation process for sulfide ores Harlowe Hardinge’s conical mill

Pebble milling used on the Witwatersrand (the Rand), South Africa Cryogenic breakage

TABLE 1.6 Full chronology of size-reduction technology (continued)

Source of Power Time Frame*	Machines and Processes
1910	Rod mills
1910	Raymond ring-roller mill (fixed ring)
1920	Multiple-compartment tube mills
1928	Loesche GmbH’s roller mill (rotating bowl)
1928	Vertical stirred ball mill
1930	Will Symons’ cone crusher
1930	Vibrating ball mill
1932	Alvah Hadsel’s wet primary autogenous mills
1933	Rosin-Rammler equation to define size distributions
1935	Tromp size separation curves
1941	Hardinge’s "electric ear” for feed control
1942	Dutch State Mines’ cyclone for coal circuits
1944	Humphrey Investment Company’s cyclone with vortex finder
1948	Hydrocyclones for ore circuits
1950	Tungsten carbide drill bits
1950	Jet mill
1951	Fred Bond’s energy-size reduction theory (Third Theory)
1952	Delay detonators
1955	Kubota Company’s tower ball mill
1956	Kelly Krebs’ hydrocyclones
1956	Broadbent-Callcott breakage-selection-classification matrix model for grinding mills
1957	Ammonium nitrate slurry explosives
1958	Jack Williamson’s load-power-feed rate controller for pebble mills
1960	Second-generation air separators with external cyclones
1960	Down-hole hammer drills
1963	Vertical high-speed "John” peg mill 205
1970	Vertical-shaft impact crushers
1975	Centrifugal mills
1975	Computer-control techniques for grinding circuits
1976	Nonelectric delay caps
1977	High-pressure grinding rolls
1980	Third-generation high-efficiency air separators
1980	Computer-simulation techniques for mineral grinding circuits
1993	High-speed horizontal disk mill
1995	Very large roller and tumbling mills for minerals (~1,000 tph)

* Most dates are indicative.