Calcium in Mineral Chromite and Ferrochrome Slags
Calcium is rarely found in chromite ores in amounts greater than a few tenths of a percent, and calcium analysis is rarely requested on ore samples. Calcium compounds are, however, used as slag conditioners for ferrochrome smelting. Most of the chromite-related samples received for calcium analysis at this Center have been slag samples. The data […]
Aluminum and Magnesium in Chromite and Ferrochrome
Aluminum and magnesium occur as gangue components in chromite ores and ferrochrome slags. At this Center, ores from many different sites and of many varieties are examined for commercial feasibility. The beneficiation of these ores is a continuing activity that produces most of the samples that are analyzed with this method. Data from this method […]
Metallic Iron in Ferrochrome Slags
It would truly be unusual to find a sample of mineral chromite with metallic iron in it. However, (his Center has handled many samples of prereduced smelter charges with several percent of metallic iron and ferrochrome slags with measurable quantities of metallic iron. Therefore, this method finds its use in the later stages of mineral […]
Ferrous Iron in Mineral Chromite and Ferrochrome Slags
The determination of ferrous iron in mineral chromites and other chromite-bearing samples is limited by the difficult solubility of the chromite lattice. Reaction of the ferrous iron immediately upon release from the crystal seems to be the preferred way of measurement. Attempts to dissolve chromite by other methods depend on strong oxidizing agents that leave […]
Total Iron in Mineral Chromite and Ferrochrome Slags
Iron is the second major element in chromite. In smelting operations where ferrochrome is the product, a specific range in the chromium-to-iron ratio is desired. Where pure metallic chromium is the product, the iron concentration is not as important. In both cases, it is important to have a good value for the chromium-to-iron ratio. A […]
Acid-Soluble or “Metallic” Chromium in Ferrochrome Slags
At this Center, results from this method have been used almost exclusively as data for the calculation of the total degree of reduction in a smelter batch, rather than as an indicator for the metallization of chromium. When a charge of chromite material is smelted or prereduced, the crystal structure is changed, and once the […]
Total Chromium in Mineral Chromite and Ferrochrome Slags
The total chromium content in mineral chromite and ferrochrome slags can range from a fraction of a percent in the slags to greater than 30 pct in the ore concentrates. Because of this variation and because of the difficulty in dissolving chromite-containing samples, the method of choice at this Center has been fusion with sodium […]
Analysis of Chromite and Ferrochrome Slag
This report describes the elemental characterization of chromite and related materials at the Bureau of Mines, Albany Research Center. Analytical methods for determining the major constituents, representing extensive experience, refinement, and development, are described and fully annotated. This presentation should allow other laboratories to use these methods and obtain comparable results with a minimum of […]
Longwall Pillar Design Method
The past decade has provided a wealth of practical experience with longwall pillar design. Design formulas developed specifically for longwalls have proven their value in numerous applications. Analytic methods, including numerical models, have also made important contributions. These advances have been based on basic research into abutment loads, coal pillar mechanics, and the interaction between […]
Grinding Ball Wear & Breakage by Impact & Abrasion Tests
Impact and abrasion properties of various commercial US grinding balls were evaluated and compared by the Bureau of Mines, US Department of the Interior. Laboratory tests were conducted on balls obtained from eight major US manufacturers. The balls included forged steel, cast steel, and alloyed white cast iron and were subjected to repeated impacts until […]