Хонинговальные головки

In this section, we make extensive use of Bond’s review of early autogenous grinding sys­tems, using his terminology for autogenous grinding (Bond 1964). Pebble milling or secondary autogenous grinding is the process in which feed pass­ing 19 mm or finer is ground by pebbles of ore with a maximum size of 76 mm or more Read more

Rock Drills in the 19th Century Humans have been drilling holes in rocks for more than 4,000 years. Drill holes used for explosives need to penetrate some distance into the rock mass; otherwise all that hap­pens when the explosive is detonated is that rock at the surface is shattered. A steam — driven rotary drill Read more

Querns for Grinding Ores Ore breakage in Greek and Roman times was mainly by human muscle power, although cattle mills were introduced about 200 bc. The usual procedure was for rocks to be bro­ken with hammers, large pebbles to be broken in mortars and pestles up to 1.5 m deep and 4 m in diameter, Read more

In 1848, William Easby was granted a patent for a method of converting fine coal into solid lumps. In his application, Easby made only one claim: “The formation of small par­ticles of any variety of coal into solid lumps by pressure.” In an equally brief description of the process, he mentions, “The utility and advantage Read more

Medium-Speed Mills A “soft size reduction” mill named the Triumph mill was made by Alpine in 1898 for pre­paring foodstuffs, animal fodder, and chemicals. The pin mill used the same principle as the colloid mill but with a lower speed of rotation. Figure 8.5 is the front page of the 1903 sales brochure. This was Read more

CHIMPANZEES AND NUT CRACKING The history we give in this book begins at the start of agriculture, about 8000 bc, and it refers only to the activities of Homo sapiens. Size reduction, however, may actually have been pioneered long before that. For example, chimpanzees in some regions of West Africa have a culture of nut Read more

The Blake crusher had its origin in a decision by the town council in New Haven, Con­necticut, in 1852 to build a 3.2-km road in the center of the town using the MacAdam process. Eli Blake was one of the townsmen responsible for planning the road, and he realized that the cost would be reduced Read more

After 1900 the grinding of Portland cement raw material and of cement clinker required large numbers of tumbling mills. This was also the heyday of gold min­ing. The old stamp mills that were used in great numbers for grinding gold ore did not grind sufficiently fine to liberate all of the gold, and the new Read more

An early invention was a static air separator in which there are no moving parts and clas­sification occurs by changes in air velocity and direction. Figure 9.8 shows the method of operation of a cone-type separator. The air stream (C) carrying the particles is converted from a directional flow through the outer cone into a Read more

In the days before digital computers, sizing distributions were often simplified to a single value, typically the size in microns through which 50% or 80% of the material passed. This was good enough for Bond’s work on circuit design but not good enough for under­standing breakage mechanisms or identifying how problems in breakage occurred. Com­plete Read more