The 16th, 19th, and 20th centuries brought seminal changes in size-reduction technology. In each case, abundant new wealth encouraged the consumption of materials, investments in new plants, and the development of new processes and machines. This, in turn, increased the demand for size-reduction machinery with greater productivity and greater energy efficiency.
In the 16th century, the Renaissance in Europe and the silver and gold flowing to Europe from New Spain in Central America created the wealth. Gold became the standard for establishing value when trading goods. To this day, possessing gold-either as the metal itself or as fashioned into jewelry, statues, tableware, or household decorations— is a measure of personal wealth and status.
During the 16th century, waterpower replaced muscle power for grinding, and black powder was used as an explosive for removing boulders from fractured rock masses.
The development of the steam engine led to the advent of the railroad and steam — powered ships, which replaced horses and wind-catching sails as the driving energy for
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TABLE 1.1 World population during the last 1,000 years and future projections
* NA = not available |
long-distance transportation by land and sea of people, materials, and goods. The use of steam power heralded the start of the 19th century’s Industrial Revolution, which created additional wealth and dramatically expanded the production of consumer and capital goods and rapidly increased the demand for minerals. During this period, many machines were invented for size reduction.
Dynamite eventually replaced black powder for breaking rocks to yield raw materials, and a new generation of mining and milling machines was invented. The development of steam power—a reliable, concentrated form of energy-started a major revolution in the distribution of materials, food, fuel, and finished products, as well as in the transportation of people. Rail transportation, first with steam locomotives and then with diesel — powered locomotives, became commonplace.
By the start of the 20th century, demand for iron, steel, copper, lead, and other metals was strong. As the century unfolded, progress in electrical, mechanical, and materials engineering made bigger and better size-reduction machines possible, and the inexorable increase in population and demand for raw materials made them necessary. At that time, the newest sources of energy—electricity and oil—were generating great wealth. In addition, the population was increasing at an astonishing rate. The demand for products that resulted from greater wealth and more people was propelling the demand for size — reduction machinery with greater productivity and energy efficiency. For example, the development of automobiles and trucks driven by internal combustion engines, and later, the dramatic growth and flexibility of the airplane, meant that more materials needed to be reduced to ever smaller sizes at ever higher efficiencies. During this era, immense size-reduction machines were constructed to meet industry needs. Principally, these industries produced flour, construction stones and aggregates, metallic and nonmetallic minerals, portland cement, and chemicals and fine powders.
The portland-cement process, the cyanide and flotation processes for minerals, and the gradual reduction process for cereal grains—all of which required efficient, high — capacity fine-grinding circuits—had been developed by the beginning of the 20th century. These processes set the stage for advances in size-reduction technology that would be made possible by the electrical age.