Aid mine workers in detecting hazardous roof conditions in underground mines by developing a method of roof sounding which supplements or replaces the traditional roof sounding technique where the miner relies on experience to determine whether or not the rock is sound. The Bureau of Mines developed an electronic roof sounding device that acoustically determines … Read more
Conventional practice for treating mine drainage and other water sources contaminated with heavy metals is lime precipitation and settling of the hydrous oxides. This produces a voluminous toxic sludge that results in another type of disposal problem. In addition, settling of the precipitated hydrous oxides often does not produce sufficiently pure water to meet statutory … Read more
Fundamental problems exist with the drying of fine coal. The moisture content of fine coal after mechanical dewatering is often too high to allow the coal to be added directly to the coarser (plus ¼ in) fractions and it must be further dewatered. Also, fine coal is lost and expelled with sludge in most current coal … Read more
Phosphatic clay waste is one of the principal waste products resulting from the mining and benefication of Florida phosphate ore. This waste material, which is comprised of ultrafine particles (70 pct less than 1 µm), responds poorly to conventional solid-liquid separation techniques and is currently disposed of by impoundment behind earthen dams. The overall natural … Read more
While grinding is unavoidable in nearly all mineral processing, it is an inefficient and costly step. As an example, the National Academy of Sciences (NAS) estimates that the copper industry consumed 205,000 tons of grinding media in 1978. A typical copper producer processing 100,000 tons of ore per day may spend approximately $25,000 daily to … Read more
From 10 to 12 million tons of cement kiln dust accumulate annually at domestic cement plants. This finely divided dust is emitted from cement kilns to prevent the buildup of excessive salts in the cement product. The alkali salts in the dust are derived from the clay raw materials, which include potassium and sodium feldspars. … Read more
Independent mine operators have difficulty marketing complex gold-silver concentrates and ores. Generally, complex sulfide concentrates and ores cannot be handled by existing smelters. Even when handling them is technically possible, smelter charges and transportation costs become limiting factors. Hydrometallurgical methods are seriously being considered to provide a simple, inexpensive, low-pollution process to treat complex gold-silver … Read more
The United States depends upon imports to supply most of the rutile and up to 70 pct of the ilmenite and titanium slag requirements for the manufacture of TiO2 pigments, titanium metal, and welding rod coatings. To help assure an adequate supply of titanium raw materials to meet national economic and strategic needs, the Bureau … Read more
A major cost factor in the sintering and smelting process for producing Pb is the control needed to meet existing environmental standards for Pb emissions. Another issue is the current concern over acid rain, which will in all probability result in even more stringent controls on emission of S gases. The method consists of (1) … Read more
We are developing improved technology to increase the recycling of mixed contaminated Cr-Co-Ni-bearing scrap and waste materials. According to a study of critical metals availability approximately 125 million lb/yr of mixed contaminated superalloy and associated heat- and corrosion-resistant high-alloy scrap is downgraded or exported. Even though Co usage has dropped in recent years, appreciable amounts … Read more