The art of prophecy is very difficult, especially with respect to the future.
—Attributed to Mark Twain
NEW SCENARIOS FOR SIZE REDUCTION
For more than 10,000 years, size reduction has been the unending effort to produce ever — larger volumes of flour for consumption, rocks and pebbles for building, and fine mineral particles for producing cement and metals. The main barriers to creating large-scale size-reduction systems, tools, and machinery were the amount of energy that a machine could utilize and the quality of those materials used to build the tools and machinery.
In the latter part of the 19th century, during the Industrial Revolution, inventions were abundant and steam was found to be superior to both waterpower and muscle power. The availability of energy and the quality of available materials to build machinery and tools, however, still limited the growth of size-reduction technology.
During the first half of the 20th century—a time of world wars and economic depression-interests other than size reduction were predominant. It was not until later that the excitement of innovation again gripped the industrial community. Engineers then began to use all the tools at their disposal—electricity, new materials, and computers— to improve all size-reduction processes and machinery.
Now, as the 21st century begins to unfold, the technical environment in which size — reduction processes operate has changed in a number of important ways.
■ Energy is available in unlimited amounts. If it is not available at a particular location, power systems can be extended to the site or a generator can be obtained.
■ Materials now available for constructing the tools and machinery have excellent resistance to wear and impact and are continually being improved.
■ Motor size and the availability of gears and pinions no longer are a barrier to construction, enabling the creation of size-reduction machines with capacities unimaginable even 50 years ago.
■ Explosions now can be designed to shatter millions of tons of rock.
■ Machines have been developed to meet numerous special requirements.
The demand for size reduction will continue to grow. The question is: What course will the technology take? Making the assumption that the path of progress followed during the last 100 years will continue unchanged probably is not prudent because of the equipment and process limitations—whether anticipated or unrecognized—that have developed.
The history of size reduction shows that, as the demand for size-reduction systems, tools, and machinery has developed, the available technology using available energy sources has met the demand, and often also has been accompanied by new processes and machinery. At the same time, the need for human muscle power has been reduced. The
181
expansion created by the Industrial Revolution, however, also increased contamination of the air, water, and soil to the extent of creating potentially harmful effects. The solutions to these environmental and societal problems also could create new demands on size-reduction technologies, systems, tools, and machinery.