Copyright held by photographer Summary Acid mine drainage AMD refers to the outflow of acidic water from a mining site. Acid mine drainage is a major problem with many hardrock mines, including almost all mines where the metal ore is bound up with sulfur metal sulfide mines. A significant number of coal mines also suffer from acid mine drainage. The metals dissolved by the acid drainage poison downstream waters, in many cases to the point where nothing other than microbes can survive.
Properties[ edit ] Calcium silicate is a white free-flowing powder. It can be derived from naturally occurring limestone and diatomaceous eartha siliceous sedimentary rock.
It has a low bulk density and high physical water absorption. Industrial-grade piping and equipment insulation is often fabricated from calcium silicate. Its fabrication is a routine part of the curriculum for insulation apprentices.
Calcium silicate competes in these realms against rockwool and proprietary insulation solids, such as perlite mixture and vermiculite bonded with sodium silicate.
Although it is popularly considered an asbestos substitute, early uses of calcium silicate for insulation still made use of asbestos fibers. Other methods for exterior protection of electrical circuits include boards made of sodium silicate bonded and pressed vermiculite and flexible wraps made of ceramic fibre and rockwool.
It is used in passive fire protection and fireproofing as calcium silicate brick or in roof tiles. It is one of the most successful materials in fireproofing in Europe because of regulations and fire safety guidelines for commercial and residential building codes see Calcium Silicate use in Europe.
Where North Americans use spray fireproofing plastersEuropeans are more likely to use cladding made of calcium silicate. For sub-standard products, silicone -treated sheets are available to fabricators to mitigate potential harm from high humidity or general presence of water.
Fabricators and installers of calcium silicate in passive fire protection often also install firestops. When this material is processed into a highly refined, re-purposed calcium silicate aggregate, it is used in the remediation of acid mine drainage AMD on active and passive mine sites. Monosilicic acid remains in the bulk solution to play other important roles in correcting the adverse effects of acidic conditions.
As opposed to limestone a popular remediation material calcium silicate effectively precipitates heavy metals and does not armor over, prolonging its effectiveness in AMD systems.Calcium silicate is commonly used as a safe alternative to asbestos for high-temperature insulation materials.
Industrial-grade piping and equipment insulation is often fabricated from calcium silicate. International Classification of Diseases, Revision 9 () [Return to International Classification of Diseases]. Acid mine drainage (AMD) or acid rock drainage (ARD) is considered as one of the main pollutants of water in many countries that have historic or current mining activities.
Its generation, release, mobility, and attenuation involves complex processes governed by a combination of physical, chemical, and biological factors.
1 Mining personnel have a different interpretation of the term “mine water management”.For the rock mechanics engineer it is the de-pressurisation of a slope in an open pit, for the metallurgist it might pertain to the water contained in the process circuit, and for the tailings engineer, the waste circuit.
Acid mine drainage is the phenomenon where metallic compounds react with the surrounding water and air to produce sulfuric acid. This is then drained in the form of streams. The effects of such drainage are very harmful, and the pH levels can even go below zero*.
pH is the most critical component, since the lower the pH, the more severe the potential effects of mine drainage on aquatic life. The overall effect of mine drainage is also dependent on the flow (dilution rate), pH, and alkalinity or buffering capacity of the receiving stream.