Control Conveyor Belt Acceleration

The part that acceleration plays in starting a belt conveyor and its effect on belt conveyor design are well understood in a general way. Its practical importance is easily overlooked, however, and under some conditions, it is absolutely necessary to give the problem of acceleration detailed study. Mathematical Analysis In working out the various problems … Read more

Dry Process Cement Plants

The heavy postwar demand for Portland Cement has created shortages that are gradually being overcome by increases in plant capacity. In the postwar period, the Lone Star Cement Corp. has expanded several of its existing 15 plants and has built 2 new plants, now in operation, with a third new plant under construction in Brazil, … Read more

Diamond Flotation

Experiments in the flotation of small diamonds from both kimberlite and alluvial deposits indicate the following conclusions: Water-repellent diamonds: Satisfactory flotation of —16 mesh diamonds, which are naturally water-repellent, may be accomplished using either Aerofloat 25 together with cresylic acid, or Du Pont B23 as frother together with kerosene as auxiliary oily conditioner or froth … Read more

Magnetic Roasting of Lean Ores

During the past few years a radically new process for the magnetic roasting of iron ores has been investigated and developed by Pickands Mather & Co. and the Erie Mining Co. in the Erie laboratory at Hibbing, Minn. This process, originally devised by Dr. P. H. Royster of Washington, D. C., involves the use of … Read more

Coal Cleaning Equipment

The relative performance of coal washing equipment, or the effectiveness with which any type or make of equipment removes impurities from coal, has been most difficult to evaluate in the past. The most widely used yardstick is the Frazer and Yancey efficiency formula developed in 1922, but Yancey in a later article states that “washers … Read more

Effects of Alkalinity on Lead Flotation

Critical pH has been defined by Wark as that pH value below which a mineral will float and above which it will not float in solutions containing a given concentration of collector but free from other depressants or activators. The relationship between mineral, collector concentration, and pH is expressed in the form of a critical … Read more

Pine Oil for Flotation Frother

This paper presents the design and operation of a frothmeter capable of measuring the frothing characteristics of pine oils and other frothing reagents. The experimental data show that the frothability of pine oil is governed by: 1—rate of aeration, 2—time of aeration, 3—height of liquid column, 4—chemical composition of pine oil, 5—pH value of solution, … Read more

Electric Furnace Melting of Copper

The final casting of refined copper has been restricted for generations by the following sequence of operations: Filling the reverberatory furnace, melting, skimming, blowing or flapping, and poling. The hoped-for 24 hr cycle, producing 300 tons or more, has been taken up largely with the necessary but time-consuming tasks of cleaning the bath, sulphur elimination, … Read more

Arc Melting of Titanium Metal

Because of the reactivity of titanium metal with all known refractories and the common atmospheric gases, melting of the metal presents numerous problems. It is necessary to provide an inert atmosphere in the furnace as well as a crucible material that will not react with the molten metal, if a ductile ingot is to be … Read more

Ultra-Fine Grinding and Classification

Fluid jet mills-employing a compressible fluid to grind materials to the sub-sieve range, was developed in the early 1930’s, and the subsequent acceptance of these units was the result of their ability to pulverize solids that, because of physical properties, could not be processed by other attrition methods, such as ball, pebble, and hammer mills. … Read more