Sodium Silicate
Basic Information Sodium silicate is the common name for compounds with the formula Na2(SiO2)nO. A well-known member of this series is sodium metasilicate, Na2SiO3. Also known as waterglass or liquid glass, these materials are available in aqueous solution and in solid form. The pure compositions are colourless or white, but commercial samples are often greenish or blue owing to the presence of iron-containing impurities.They are used in cements, passive fire protection, textile and lumber processing, refractories, and automobiles. Sodium carbonateand silicon dioxide react when molten to form sodium silicate and carbon dioxide: Na2CO3 + SiO2 → Na2SiO3 + CO2 Sodium silicate is one of several chemicals that are composed of sodium, silica, and oxygen. The term is often used to indicate sodium metasilicate, which is also known as liquid glass. Sodium silicate melts at a very high temperature, making it useful for commercial fire-proofing. A sodium silicate compound contains sodium oxide, Na2O, and silica, Si2O, or a mixture of these compounds. They can be associated with up to nine molecules of water, or lack water and be known as anhydrous. These compounds can be solid, or they can be liquids. The solid version is widely used to make silica gel — a common drying agent.The combination of being liquid and being resistant to high heat makes these compounds useful for automobile repair. A sodium silicate solution is circulated from the radiator to seal leaks in the head gasket. This solution can also be used instead of motor oil to permanently disable a car engine prior to the auto’s destruction. The liquid version is also useful to treat concrete to make it more water repellent. Sodium silicate water solutions bind solids well, forming insulation boards that tolerate high temperatures. This property enables them to be used to as a refractory—retaining strength at high temperatures. Due to this, they can be used as linings in kilns and glass-making equipment. If water-proofed, they can be used as passive fire protection, such as being incorporated into the structure for plastic pipes, to form firestop devices. Sodium meta silicate is a strong base that is used in a variety of detergents as a substitute for phosphates, which have been responsible for a great deal of water pollution, by causing algae blooms. It acts primarily by changing the pH of the water to inactivate water hardness. Technically, it is known as a builder. Another sodium silicate compound is sodium aluminum silicate, which is also known as sodium aluminium silicate. It is composed of sodium, silica, oxygen, and aluminum. It can also be found in an anhydrous form, or combined with water. Sodium aluminum silicate can form very attractive minerals, including jadeite, which comprises one form of the gemstone jade. Another mineral is albite. These minerals are anhydrous. There is a synthetic, industrial form of sodium aluminum silicate that contains water. It is known as synthetic amorphous sodium aluminosilicate. This is a common food additive, used as an anti-caking agent that keeps powdered foods free of lumps. USES of Sodium Silicate: Adhesive The largest application of sodium silicate solutions is a cement for producing cardboard. When used as a paper cement, the tendency is for the sodium silicate joint eventually to crack within a few years, at which point it no longer holds the paper surfaces cemented together. Drilling fluids Sodium silicate is frequently used in drilling fluids to stabilize borehole wells and to avoid the collapse of bore walls. It is particularly useful when drill holes pass through argillaceous formations containing swelling clay minerals such as smectite or montmorillonite. Detergent auxiliaries It is used in detergent auxiliaries such as complex sodium disilicate and modified sodium disilicate. The detergent granules gain their ruggedness from a coating of silicates. Water treatment Water glass is used as coagulant/deflocculant agent in wastewater treatment plants. Waterglass binds to colloidal molecules, creating larger aggregates that sink to the bottom of the water column. The microscopic negatively charged particles suspended in water interact with sodium silicate. Their electrical double layer collapses due to the increase ofionic strength caused by the addition of sodium silicate (doubly negatively charged anion accompanied by two sodium cations) and they subsequently aggregate. This process is called coagulation/deflocculation. Refractory use Water glass is a useful binder of solids, such as vermiculite and perlite. When blended with the aforementioned lightweight aggregates, water glass can be used to make hard, high-temperature insulation boards used for refractories, passive fire protection and high temperature insulations, such as moulded pipe insulation applications. When mixed with finely divided mineral powders, such as vermiculite dust (which is common scrap from the exfoliation process), one can produce high temperature adhesives. The intumescence disappears in the presence of finely divided mineral dust, whereby the waterglass becomes a mere matrix. Waterglass is inexpensive and abundantly available, which makes its use popular in many refractory applications. Dye auxiliary Sodium silicate solution is used as a fixative for hand dyeing with reactive dyes that require a high pH to react with the textile fiber. After the dye is applied to a cellulose-based fabric, such as cotton or rayon, or onto silk, it is allowed to dry, after which the sodium silicate is painted on to the dyed fabric, covered with plastic to retain moisture, and left to react for an hour at room temperature. Food preservation World War I poster suggesting the use of waterglass to preserve eggs (lower right).Sodium silicate was also used as an egg preservation agent through the early 20th century with large success. When fresh eggs are immersed in it, bacteria which cause the eggs to spoil are kept out and water is kept in. Eggs can be kept fresh using this method for up to five months. When boiling eggs preserved this way, it is well advised to pin-prick the egg to allow steam to escape because the shell is no longer porous. Metal Repair Sodium silicate is used, along with magnesium silicate, in muffler repair and fitting paste. When dissolved in water, both sodium silicate and magnesium silicate form a thick paste that is easy to apply. When the exhaust system of an internal combustion engine heats up to itsoperating temperature, the heat drives out all of the excess water from the paste. The silicate compounds that are left over have glass-like properties, making a temporary, brittle repair. Safe construction A mixture of sodium silicate and sawdust has been used in between the double skin of certain safes. This not only makes them more fire resistant, but also makes cutting them open with an oxyacetylene torch extremely difficult due to the smoke emitted. Crystal gardens When crystals of a number of metallic salts are dropped into a solution of water glass, simple or branching stalagmites of coloured metal silicates are formed. This phenomenon has been used by manufacturers of toys and chemistry sets to provide instructive enjoyment to many generations of children from the early 20th century until the present. An early mention of crystals of metallic salts forming a “chemical garden” in sodium silicate is found in the 1946 Modern Mechanix magazine.[15][/15] Metal salts used included the sulfates and/or chlorides of copper, cobalt, iron, nickel, and manganese.
...moreSilica Sand
Basic Information Silica is the name given to a group of minerals composed of silicon and oxygen.Theseare the two most available in large quantity elements in the crust of earth. Silica is mostly found in the crystalline state and veryrarely in an amorphous state. Silica is composed of one atom of silicon and two atoms of oxygen resulting in the chemical formula as SiO2 Industrial Sand Applications Glassmaking Metal Casting Industrial sand is an essential part of the ferrous and non-ferrous foundry industry. Metal parts ranging from engine blocks to sink faucets are cast in a sand and clay mould to produce the external shape, and a resin bonded core that creates the desired internal shape. Silica’s high fusion point (1760°C) and low rate of thermal expansion produce stable cores and moulds compatible with all pouring temperatures and alloy systems. Its chemical purity also helps prevent interaction with catalysts or curing rate of chemical binders. Following the casting process, core sand can be thermally or mechanically recycled to produce new cores or moulds. Metallurgical Industrial sand plays a critical role in the production of a wide variety of ferrous and non-ferrous metals. In metal production, silica sand operates as a flux to lower the melting point and viscosity of the slag to make them more reactive and efficient. Lump silica is used either alone or in conjunction with lime to achieve the desired base/acid ratio required for purification. These base metals can be further refined and modified with other ingredients to achieve specific properties such as high strength, corrosion resistance or electrical conductivity. Ferroalloys are essential to specialty steel production, and industrial sand is used by the steel and foundry industries for de-oxidation and grain refinement. Chemical Production Silicon-based chemicals are the foundation of thousands of everyday applications ranging from food processing to soap and dye production. In this case, SiO2 is reduced to silicon metal by coke in an arc furnace, to produce the Si precursor of other chemical processes. Industrial sand is the main component in chemicals such as sodium silicate, silicon tetrachloride and silicon gels. These chemicals are used in products like household and industrial cleaners, to manufacture fiber optics and to remove impurities from cooking oil and brewed beverages. Building Products Industrial sand is the primary structural component in a wide variety of building and construction products. Whole grain silica is put to use in flooring compounds, mortars, specialty cements, stucco, roofing shingles, skid resistant surfaces and asphalt mixtures to provide packing density and flexural strength without adversely affecting the chemical properties of the binding system. Ground silica performs as a functional extender to add durability and anti-corrosion and weathering properties in epoxy based compounds, sealants and caulks. Paint and Coatings Paint formulators select micron-sized industrial sands to improve the appearance and durability of architectural and industrial paint and coatings. High purity silica contributes critical performance properties such as brightness and reflectance, color consistency, and oil absorption. In architectural paints, silica fillers improve tint retention, durability, and resistance to dirt, mildew, cracking and weathering. Low oil absorption allows increased pigment loading for improved finish color. In marine and maintenance coatings, the durability of silica imparts excellent abrasion and corrosion resistance. Ceramics & Refractories Ground silica is an essential component of the glaze and body formulations of all types of ceramic products, including tableware, sanitary ware and floor and wall tile. In the ceramic body, silica is the skeletal structure upon which clays and flux components attach. The SiO2 contribution is used to modify thermal expansion, regulate drying and shrinkage, and improve structural integrity and appearance. Silica products are also used as the primary aggregate in both shape and monolithic type refractories to provide high temperature resistance to acidic attack in industrial furnaces. Filtration and Water Production Industrial sand is used in the filtration of drinking water, the processing of wastewater and the production of water from wells. Uniform grain shapes and grain size distributions produce efficient filtration bed operation in removal of contaminants in both potable water and wastewater. Chemically inert, silica will not degrade or react when it comes in contact with acids, contaminants, volatile organics or solvents. Silica gravel is used as packing material in deep-water wells to increase yield from the aquifer by expanding the permeable zone around the well screen and preventing the infiltration of fine particles from the formation. Oil and Gas Recovery Known commonly as proppant, or “fracsand,” industrial sand is pumped down holes in deep well applications to prop open rock fissures and increase the flow rate of natural gas or oil. In this specialized application round, whole grain deposits are used to maximize permeability and prevent formation cuttings from entering the well bore. Silica’s hardness and its overall structural integrity combine to deliver the required crush resistance of the high pressures present in wells up to 2,450 meters deep. Its chemical purity is required to resist chemical attack in corrosive environments.
...moreBentonite
Bentonite is an absorbent aluminium phyllosilicate, impure clay consisting mostly of montmorillonite.The different types of bentonite are each named after the respective dominant element, such as potassium (K), sodium (Na), calcium (Ca), and aluminium (Al). Types Sodium bentonite Sodium bentonite expands when wet, absorbing as much as several times its dry mass in water. Because of its excellent colloidal properties, it is often used in drilling mud foroil and gas wells and boreholes for geotechnical and environmental investigations. The property of swelling also makes sodium bentonite useful as a sealant, since it provides a self-sealing, low permeability barrier. It is used to line the base of landfills, for example. Various surface modifications to sodium bentonite improve some rheological or sealing performance in geoenvironmental applications, for example, the addition of polymers. Calcium bentonite Calcium bentonite is a useful adsorbent of ions in solution, as well as fats and oils. It is the main active ingredient of fuller’s earth, probably one of the earliest industrial cleaning agents. Calcium bentonite may be converted to sodium bentonite (termed sodium beneficiation or sodium activation) to exhibit many of sodium bentonite’s properties by an ion exchange process. In common usage, this means adding 5–10% of a soluble sodium salt such as sodium carbonate to wet bentonite, mixing well, and allowing time for the ion exchange to take place and water to remove the exchanged calcium. Some properties, such as viscosity and fluid loss of suspensions, of sodium-beneficiated calcium bentonite (or sodium-activated bentonite) may not be fully equivalent to those of natural sodium bentonite. For example, residual calcium carbonates (formed if exchanged cations are insufficiently removed) may result in inferior performance of the bentonite in geosynthetic liners. Potassium bentonite Also known as potash bentonite or K-bentonite, potassium bentonite is a potassium-rich illitic clay formed from alteration of volcanic ash. Uses The main uses of bentonite are for drilling mud, binder (e.g. foundry-sand bond, iron ore pelletizer), purifier, absorbent (e.g. pet litter), and as a groundwater barrier.
...moreBall Clay
Ball clays are kaolinitic sedimentary clays, that commonly consist of 20-80% kaolinite, 10-25% mica, 6-65% quartz. Localized seams in the same deposit have variations in composition, including the quantity of the major minerals, accessory minerals and carbonaceous materials such as lignite. They are fine-grained and plastic in nature, and, unlike most earthenware clays, produce a fine quality white-coloured pottery body when fired, which is the key to their popularity with potters. Uses Sanitary Ware A ‘ceramic body’ for sanitaryware typically includes 30% ball clay to provide plasticity and workability, 20% kaolin, 30% feldspar and 20% quartz/silica. Tableware Ceramic tableware utilizes ball clay to provide high plasticity and a good white-fired color, combined with kaolin, feldspar and quartz. Wall and floor tiles Combined with talc, feldspar, quartz/silica and kaolin, ball clays are utilized for their plasticity and bonding properties. Glazes and engobes Ball clays are also used in the production of coatings for ceramic products to ensure the perfect finish. Refractory clays An ability to resist the effects of extremely high temperatures makes ball clay ideal for use in refractory products such as kiln insulation and furniture. Construction ceramics Building materials such as bricks, clay pipes and roof tiles all contain ball clay. Electrical porcelain insulators You will find ball clays in the electrical porcelain components that provide insulation from high voltage currents. Non-ceramic applications These include the construction industry; horticulture, agriculture and amenity industries; use as fillers and extenders in polymers, adhesives, plastics, sealants, fertilizers and insecticides.
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