Electrorefining Chromium

The Federal Bureau of Mines refined chromium from an aqueous electrolytic process in molten sodium chloride-chromium chloride electrolytes. Oxygen and nitrogen contents were reduced by a factor of 10 to 40, but most other impurities were little changed. The product usually contained a little more iron than the feed. Since iron was entering the bath … Read more

Gasification of Coal Water Slurry

The results were surprisingly reproducible in view of the complex reactions, and the scatter of data was small. Rank of coal exerted the greatest effect on gasification. Tests with only three ranks of coals do not permit firm conclusions about the effect of rank. However, work in progress reveals the same trend for other ranks … Read more

Recover Chromite by Flotation

This report describes an investigation by the Bureau of Mines of flotation techniques for the recovery of chromite from fine-grained disseminated ores. Reported work on the concentration of chromiferous materials shows that flotation has been applied almost exclusively to slime-free pulps. Therefore, chromium recoveries that could be obtained by flotation were related to the amount … Read more

Extraction Separation & Purification of Rare Earth Elements

In separating and purifying rare-earth compounds, ion-exchange and liquid-liquid extraction techniques have exhibited the greatest potential. Of the two, ion exchange has received major attention and has been exploited into commercial operation. Notable research has been reported on solvent extraction techniques, especially in extraction of tetravalent cerium with phosphates and phosphonates. Work along this line … Read more


Leonardite is a coallike substance, similar in structure and composition to lignitic coal and believed to be derived from lignitic coal by the process of natural oxidation. Leonardite is little known outside lignite-producing areas and has been developed commercially only tn a minor extent. The higher oxygen content and less compact structure of leonardite, compared … Read more

Electrowinning & Refining Ceric Oxide and Cerous Fluoride to Cerium Ingot

The metallurgical laboratory data developed in this study indicate an improved electrowinning process for producing higher purity cerium ingot. Equipment under development included the molten-bath container or electrolytic cell, electrodes, and related items, as well as an enclosure or cell box resembling that of a vacuum furnace. The cell box is designed to allow molten … Read more

Testing Method Mine Anchorage Roof Bolts

Two methods of testing anchorages of headed expansion-type mine roof bolts were investigated by the Federal Bureau of Mines to determine whether they are acceptable for general use. In both methods a load was applied to a tightened bolt with a hydraulic jack. A total of 80 tests, 40 using each method, was conducted in … Read more

What is the Best Coal for Coke Making

Selection of a suitable coal or coals for the manufacture of coke of desired quality with due consideration of the purpose for which the coke is intended requires careful thought, and often it will pay to go to considerable expense in testing such coals as may be available. In general it will always be possible … Read more

Rare-Earth Elements Electronegativity

The rare-earth metals can be fitted into Pauling’s electronegativity scale if it is modified to take highly ionic bonds into account. Good agreement between theory and experiment is obtained only for metals of groups Ia, Ila, and IIIa of the periodic table, but here it is good enough to permit estimation of unknown heats of … Read more

Bucket Elevators

Bucket elevators are used for the elevation of dry or pulped ore. They consist of an endless chain or belt carrying the buckets vertically or at a steep angle. On reaching the top pulley they should turn at sufficient speed to fling their contents out with a measure of centrifugal force. The feed is directed into … Read more