Mills Raymond

The Raymond ring-roll mill with its internal air separation is widely used to pulverize phenolformaldehyde resins. The usual fineness of grind is finer than 99 percent minus 200 mesh. Air at 4°C (40°F) is usually introduced into the mill to limit temperature rise. A typical 3036 Raymond mill using 34 kW (45 hp) will produce better than 900 kg/h (2000 Ib/h) at 99 percent minus 200 mesh. 

Raymond mill or sf-eam jet mill Coarse size reduction, wet tubular mill... 

The general pieces of equipment used in grinding flake mica or mica concentrate into saleable mica products are hammer mills of various types, fluid energy mills, Chaser or Muller mills for wet grinding, and Raymond or WiUiams high side roUer mills. Another method is being developed, called a Duncan mill (f. M. Huber, Inc.), that is similar in many respects to an attrition mill. AH of these mills are used in conjunction with sieves, and all but some types of hammer mills incorporate air classifiers as a part of the circuit. 

Figure 12-96 illustrates a single-stage dryer employing a paddle mixer, recycle, and an ABB Raymond cage mill for tine grinding and... 

TABLE 12-33 Sizes and Capacities of ABB-Raymond Cage-Mill Flash-Drying Systems ... 

There are several mechanical air classifiers designed to operate in the superfine 10- to 90- Im range. Two of these are the Mikroplex spiral air classifier MP T Hosokawa Micron Powder Systems Div.) and the classifier which is an intregal part of the Hurricane pulverizer-classifier ABB Raymond Div, Combustion Engineering Inc.) described under Hammer Mills. Others are the Majac classifier Hosokawa Micron Powder Systems Div.), the Sturtevant Superfine Air Separator, and the Bradley RMC classifier. These also use a vaned rotor, but operate at higher speed with higher power input and lower throughput. 

Hammer Mills with Internal Air Classifiers The rotating components of the Raymond vertical mill are carried on its vertical shaft. They are the grinding element, double-whizzer classifier, and fan, as shown in Fig. 20-49. This mill has a hammer-tip speed of 7600 m/min (25,000 ft/min), so that it is effective for finer grinding than the Imp mill, which has a tip speed of 6400 m/min (21,000 ft/min). 

FIG. 20-50 Raymo nd high-side mill with an internal whizzer classifier. (ABB Raymond Div., Combustion Engineeiing Inc.)... 

High-speed hammer mills are extensively used for the grinding of soya flour. For example, the Raymond Imp mill with an air classifier is used, primarily with solvent-extracted soya. 

Mined clay with 22 percent moisture is broken up into pieces of less than 5 cm (2 in) in a rotary impact mill without screen, and fed to a rotary gas-fired lain for drying (see Fig. 20-58). The moisture content is then 8 to lOpercent, and this material is fed to a miU, usually a Raymond ring-roll mill with an internal whizzer classifier or a pan mill. Hot gases introduced to the mill complete the diying while the material is being pulverized to the required fineness. 

The mills in the western United States, in which generally are ground softer talcs than those of New York, have simple flow sheets. Single-stage crushing is employed, and the talc is merely ground in Raymond roller mills in closed circuit with air separators. 

A Raymond 5057 ring-roller mill pulverizing fluorspar produces 4500 kg (10,000 lb) of product per hour 95 percent minus 200 mesh with 104 kW (140-hp) operating power, or 26 kWh/Mg (23.4 k 4i/ ton). Fluorspar is also ground in continuous-tube mills with classification. 

Lead Oxides Leady litharge containing 25 to 30 percent free lead is required for storage-batteiy plates. It is processed on Raymond Imp mills. They have the ability to produce litharge that has a desired low density of 1.1 to 1.3 ff/cm (18 to 22 g/iu ). A 56-kW (75-hp) unit produces 860 kg/h (1900 Ib/h) of materialhaving this density. 

Sulfur The riug-roUer mill can be used for the fine grinding of sulfur. Inert gases are supplied instead of hot air (see Properties of Sohds Safety for use of inert gas). Performance of a Raymond No. 5057 ring-roller mill is given in Table 20-34. The total cost might be 3 to 4 times the power cost and include labor, inert gas, maintenance, and fixed charges. 

Theil, E. C. Raymond, K. M. Transition-Metal Storage, Transport, and Biomineralization University Science Books Mill Valley, CA, 1994. 

Herbert T. Pratt. Textile Mill Scale-Up of Nylon Hosiery, 1937-1938. In Manmade Fibers Their Origin and Development. Raymond B. Seymour and Roger S. Porter, eds. London Elsevier Applied Science, 1993. Source for marketing nylon and 80 percent of silk for hosiery in United States. 

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