Хонинговальные головки

Fred Bond was the engineer who did much to define the relationship between ore hard­ness, tonnage processed, size reduction achieved, and power required. Born in 1899 and raised in a rural community near Golden, Colorado, he attended and graduated with honors from the Colorado School of Mines (CSM) with a bachelor’s degree in metallurgy. He […]

A seminal change in flour milling occurred in 1785 when Oliver Evans built an automatic flour mill to eliminate manual labor in material handling (Figure 4.9). Previously, sev­eral stages of grinding had been required, which included manual sifting between the stages to remove finished flour and inedible particles and to winnow out coarse materi­als for […]

The main uses of coal are as fuel in furnaces and as a chemical to reduce iron oxides to iron. To meet environmental standards for these purposes, coal needs to be mined, crushed, separated by size, upgraded, and ground to burn efficiently with the gaseous and solid wastes. Ground limestone is also required to remove […]

The use of a mixture to bind materials—called “mortar”—to hold rocks together in a building or wall was developed in the Stone Age, and, by 1811, burnt lime had been used as a cement for more than 2,000 years. In that year, Joseph Aspdin, an English mason, burned a mixture of lime and clay and […]

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 […]

Classifiers are devices for subjecting comminuted ore to the action of water either in such a way that a division of the ore particles is made into two or more prod­ucts according to relative settling powers, or in such a way that all the ore material is settled together for dewatering purposes. …Classifiers all have […]

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 […]

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 […]

The advent of steam power greatly improved the efficiency of flour mills. In 1786, two 37-kW steam engines were connected to drive 20 stone mills (1.5 m in diameter) at the Albion grain mill in London (Fischer 1944), and for the next 100 years, grain was ground mainly in steam-driven querns. A flour mill that […]

Impact breakage processes are used to reduce the size of hard, brittle materials but are not useful for reducing soft or elastic materials unless the materials can be cooled to the point at which they become brittle. This is where cryogenic breakage is becoming very important. Its main use is in recycling processes for plastic […]