Filler dolomite

Carbonates and Sulfates Carbonates include limestone, cal-cite, marble, marls, chalk, dolomite, and magnesite the most important sulfates are barite, celestite, anhydrite, and gypsum these are used as fillers in paint, paper, and rubber. (Gypsum and anhydrite are discussed below as part of the cement, lime, and gypsum industries.)... 

These methods are the principal ones used in the production of fillers based on calcium carbonate and dolomite, clays, talcs, micas and wollastonite. These fillers, on a volume basis, dominate the industry. 

Proebster, M. (1988) Propellant liners containing dolomite filler for heat resistance in rockets. Ger. Offen DE 3,643,825 Chem. Abstr., (1988) 109,... 

The resulting AN solution may be handled in various ways103. It can be stored as a solution, used in down-stream plants or sold as a solution it can be formed into solid AN by prilling or granulation, or it can be mixed with a solid filler. The most common filler is calcium carbonate in the form of ground limestone, dolomite or by-product calcium carbonate. This product is known as Calcium Ammonium Nitrate (CAN) and can be prilled or granulated. Granular products that contain AN and either ammonium or calcium sulphate are also manufactured. 

Calcium carbonate is the most commonly used extender. It is widely available and low in cost, and it provides for improvements in certain performance properties. The material is a mineral that is mined throughout the world. Common forms of calcium carbonate include limestone, marble, calcite, chalk, and dolomite. It is manufactured by precipitation processes and is commercially available from a number of sources. Calcium carbonate is available in many different particle sizes and in various grades. To improve dispersion in certain resins, the filler is often coated with calcium stearate or stearic acid. 

Ground dolomite (calcium magnesium carbonate) and limestone fillers are also used. 

Inexpensive, finely ground minerals like barium sulfate (barytes), dolomite, limestone (whiting), clays, and silica are widely used to provide bulk and reduce the cost of friction material formulations. These materials also act as friction modifiers and alter the performance of the end product. Other less commonly used fillers are hollow and solid organic and inorganic microspheres and fly ash. 

Calcium carbonate and dolomite filler and extenders. Omya/Pliiss-Staufer AG. Technical Note 19. 

Typical fillers carbon black, calcium carbonate, dolomite, clays, calcinated clays, talc, soapstone, zinc oxide, filmed silica, borates, iron oxide, zinc oxide, magnesium carbonate, pulverized polyurethane foam, barium and strontium ferrites, magnesium aluminum silicate, nylon fibers, quartz in EMI shielding field silver plated aluminum, silver plated nickel, silver coated glass spheres, silver plated copper, silver, nickel and carbon black... 

The binder can be calcium lime, dolomitic lime, a hydraulic lime, a lime-cement mix, or cement. When calcium lime, or Type S dolomitic lime is mixed with sand to produce a sand-lime mortar, its initial role is that of a void filler. It subsequently causes the mortar to harden slowly, as a result of carbonation of the calcium hydroxide (N.B. when the term lime is used in connection with mortars, it refers to fully slaked lime with a low expansion potential. This includes Type S dolomitic times, which are widely used for mortars in the USA). 

Examples of a few are alpha cellulose, ash, calcium carbide, calcium carbonate, carborundum, channel black, china clay, coral, coke dust, diatomaceous earth, dolomite [double carbonate of lime and magnesia filler having the formula (CaCOg) and (MgCOg)], ferrite, flint, fixller s earth, glass spheres, hemp, keratin, lampblack, leather-dust, macerate... 

Cement, lime, limestone filler and filler from other rocks, such as a mixture of diabase and dolomite, as well as sulfur filler, were used in the past (Fiber and Pichler 1993). A substantial effect on the permanent deformation behaviour was seen only with the use of sulfur (Denning and Carswell 1981b Fromm and Kennepohl 1979). 

For conventional mineral fillers such as calcium carbonate, dolomite, mica, and wollastonite, the chemistry of each is constant across all grades of a given material and the grades are differentiated by their particle size, size distribution, particle shape, and presence (or otherwise) ofa surface treatment. In the case of POSS, every grade is chemically distinct and so properties such as density, polarity, refractive index, and so on, are different for each POSS [8] (Table 23.1). 

Abrasion can be serious when using mineral fillers. Fillers with alpha-quartz components have by far the highest abrasion rate, but heavy and tabular spars and dolomite also show high abrasion compared with some calcium carbonates. The measurement value usually cited is the Mohs hardness scale, but this is not a decisive indicator. 

---