АСБЕСТА химические свойства, назначение, производство
Описание
Asbestos is a fibrous silicate of
magnesium and calcium. However, the “extender”,
known as “asbestine”, that has come to the forefront in
paint making, is really a ring silicate of magnesia and
slightly alkaline, but without the fibrous texture of
asbestos or amianth. Asbestine pulp (as a certain variety
of the material mined at the foot of the Adirondack
mountains is known to the trade), although it is sold
in the dry powdered form, belongs really to the soapstone
or talc variety. But it is not as unctuous as either
of those, has a harder texture, and is of whiter color
than either soapstone or talc.
Химические свойства
TREMOLITE, the mineral tremolite is a calciummagnesium silicate corresponding to the formula Ca2Mg5Si8O22(OH)2, belonging to the amphibole group. The replacement of magnesium by ferrous iron causes tremolite to approach actinolite in composition. Tremolite is monoclinic, developing bladed prismatic crystals, but it is frequently found in compact columnar, granular, or fibrous masses. The perfect prismatic cleavage at angles of 56° and 124° typical of this group is to be noted; hardness, 5–6; specific gravity, 2.9–3.1; luster, vitreous to silky; color, varies from white or whitish-gray through shades of green or greenish-yellow; transparent to opaque. Tremolite is formed as a result of contact metamorphism and occurs in marbles, dolomites, and schists. It may alter to talc.
Физические свойства
White or greenish (chrysotile), Blue (crocidolite), or gray-green (amosite) fibrous, odorless solids; freezing/ melting point5600 C (Decomposes). Hazard identification (based on NFPA-704 M Rating System): Health 2; flammability 0; reactivity 0. Insoluble in water. Asbestos is a generic term that applies to a number of naturally occurring, hydrated mineral silicates incombustible in air and separable into filaments. The most widely used in industry in the United States is chrysotile, a fibrous form of serpentine. Other types include amosite, crocidolite, tremolite, anthophyllite, and actinolite.
Использование
Asbestine pulp or asbestine in its
various varieties has been used for many years by
manufacturers of paints, not so much as an adulterant,
but rather to make the paint more buoyant in order to
keep it from settling to any extent, as this compound is
of very low-specific gravity and a great oil absorber.
Определение
A fibrous variety
of various rock-forming silicate minerals,
such as the amphiboles and chrysotile. It
has many uses that employ its properties of
heat-resistance and chemical inertness.
Prolonged exposure to asbestos dust may
cause asbestosis – a form of lung cancer.
Общее описание
Any of a group of impure magnesium silicate minerals that occur as slender, strong, flexible fibers. Colors range from white to gray, green, brown. Resistant to fire and most solvents. Breathing of ASBESTOS dust causes ASBESTOSis and lung cancer. Used as a heat resistant material, in cement, furnace bricks, and in brake linings.
Реакции воздуха и воды
Insoluble in water.
Профиль реактивности
ASBESTOS minerals are generally unreactive.
Опасность
Inhalation of dust or fine particles is dangerous.
Carcinogenic.
Пожароопасность
Some may burn but none ignite readily. Containers may explode when heated. Some may be transported hot.
Промышленное использование
Any of six naturally occurring minerals characterizedby being extremely fibrous (asbestiform),strong, and incombustible. They areutilized in commerce for fire protection; asreinforcing material for tiles, plastics, andcements; for friction materials; and for thousandsof other uses. Because of a great concernover the health effects of asbestos, many countries have promulgated strict regulationsfor its use. The six minerals designated asasbestos also occur in a nonfibrous form. Inaddition, there are many other minerals thatmorphologically mimic asbestos because oftheir fibrous nature.
The important characteristics of the asbestosminerals that make them unique are theirfibrous form; high strength and surface area;resistance to heat, acids, moisture, and weathering;and good bonding characteristics withmost binders such as resins and cement.
Asbestos is used for many types of products because of its chemical and thermal stability, high tensile strength, flexibility, low electrical conductivity, and large surface area. Past uses of asbestos, such as sprayed-on insulation, where the fibers may become easily airborne, have been generally abandoned. Asbestos is used predominantly for the construction industry in the form of cement sheets, coatings, pipes, and roofing products. Additional important uses are for reinforcing plastics and tiles, for friction materials, and packings and gaskets.
Профиль безопасности
Confirmed human
carcinogen producing lung tumors.
Experimental neoplastigenic and
tumorigenic data. Human pulmonary system
effects by inhalation. Usually at least 4 to 7
years of exposure are required before
serious lung damage (fibrosis) results.
Mutation data reported. A common air
contaminant.
Возможный контакт
Most asbestos is used in the construction
industry. Much of it is firmly bonded, i.e., the asbestos
is “locked in” in such products as floor tiles, asbestos
cements, and roofing felts, and shingles; while the remaining
8% is friable or in powder forms present in insulation
materials, asbestos cement powders, and acoustical products.
As expected, these latter materials generate more airborne
fibers than the firmly bonded products. The asbestos
used in nonconstruction industries is utilized in such products
as textiles; friction material including brake linings
and clutch facings; paper, paints, plastics, roof coatings;
floor tiles, and miscellaneous other products. Significant
quantities of asbestos fibers appear in rivers and streams
draining from areas where asbestos-rock outcroppings are
found. Some of these outcroppings are being mined.
Asbestos fibers have been found in a number of drinking
water supplies, but the health implications of ingesting
asbestos are not fully documented. Emissions of asbestos
fibers into water and air are known to result from mining
and processing of some minerals. Exposure to asbestos
fibers may occur throughout urban environments perhaps
resulting from asbestos from brake linings and the flaking
of sprayed asbestos insulation material. In recent years,
much effort has been put into removal of asbestos insulation,
particularly from schools and other public buildings
where worn or exposed asbestos causes public exposure.
Incompatibilities: None
Канцерогенность
Asbestos and all commercial forms of asbestos are known to be human carcinogens based on sufficient evidence of carcinogenicity from
studies in humans.
Перевозки
UN2212 Blue asbestos (Crocidolite) or Brown
asbestos (amosite, mysorite), Hazard class: 9; Labels:
9-Miscellaneous hazardous material. UN2590 White asbestos
(chrysotile, actinolite, anthophyllite, tremolite), Hazard
class: 9; Labels: 9-Miscellaneous hazardous material.
Утилизация отходов
Asbestos may be recovered
from waste asbestos slurries as an alternative to disposal.
Landfilling is an option for disposal if carefully
controlled.
АСБЕСТА препаратная продукция и сырье
сырьё
препарат