Хонинговальные головки

Regardless of the category, all tumbling mills operate on the same principles: ■ The total weight of the charge in the mill—the sum of the weight of the grinding media, the weight of the material to be ground, and any water in the mill—is a function of the percentage of the volume of the mill […]

Most of the grinding of coal for combustion burners is performed in roller mills, but air — swept dry-grinding ball mills operating in closed circuit with separators are also used. Coal is fed to the ball mill with heated air. The air is drawn through the mill by a fanlocated in the classifying section. The […]

Another method of keeping balls in motion at high speed is nutation, which is similar to the oscillation of a spinning top. The nutating action, shown in Figure 8.9, is used by the Hicom mill. The grinding chamber is a truncated cone with a roughly hemispherical base, on a vertical axis of symmetry. The chamber […]

An initiation system starts the detonation of the main charge, after which firings should occur at the exact times that are planned to ensure best results. As discussed earlier, the objective of initiation systems during the black powder and dynamite eras was to improve the safety of explosives. By 1900, the first electric delay detonator […]

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 […]