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This report covers the sodium and potassium silicates and the silicas and silicates derived from sodium silicate—precipitated and colloidal silica and silica gel and calcium and magnesium silicates. It also includes two other specialty amorphous silicas—fumed and fused—and ethyl silicate, which is used in markets similar to those of colloidal silica. In addition to being used as sources of buffered alkalinity and corrosion protection, the soluble silicates find use as binders, as do colloidal silica and ethyl silicate. A number of the silicas and precipitated silicates—precipitated, gel and fumed silica and calcium silicate—are used as specialty fillers, carriers and flow-control agents.
Precipitated and colloidal silicas (silica sols) and silica gels are usually produced commercially from sodium silicate. These derivative silicas are amorphous (noncrystalline) and water insoluble, characterized by different physical properties such as surface area, particle size, pore size and shape. These silicas are commercially available in a variety of grades suited for many different industrial applications.
For a number of these specialty silicas and silicates, the production technology is relatively closely held, with participants serving global markets, frequently in joint ventures. Some producers concentrate on a single product worldwide. In other instances, companies may produce more than one silicate derivative, or even another specialty silica produced with unrelated technology. Increasingly, the major producers are participating in global markets. There have been a number of mergers and acquisitions in recent years. In early July 2008, an agreement was completed to combine INEOS Silicas and PQ Corporation (owned by The Carlyle Group). The new company is called PQ Corporation. The Carlyle Group will hold a 60% share and INEOS Capital the remaining 40% of the new company.
Although some sodium silicates are produced as solids (primarily metasilicates), the majority are liquids that cannot cost-effectively be transported long distances. Consequently, producers tend to size plants to local requirements. Silicate producers tend to group into two categories: merchant producers, which frequently also supply other complementary, commodity chemicals; and producers of silicate derivatives such as specialty silicas, or zeolites for detergent or catalyst use. The latter may or may not also serve the merchant market. The typical resulting pattern, therefore, is of relatively small silicate plants interspersed with larger dedicated units where required for derivatives production. A significant fraction of total sodium silicate production is destined for the captive downstream production of derivatives, although sodium silicates also have important direct uses.
Potassium silicates are more water soluble than sodium silicates and more fire resistant than other silicas. Potassium silicates eliminate problems associated with sodium ions in a number of applications (e.g., efflorescence in coatings).
Calcium and magnesium silicates are amorphous, water-insoluble powders precipitated from sodium silicate solutions, which function as specialty carriers (especially of oils), flow-control agents and fillers. Ethyl silicate is a colorless liquid used primarily as a ceramic binder and in inorganic zinc-rich coatings. It also hydrolyzes readily to silica in water and can thus serve as a pure silica source for specialized silica gels.
Precipitated silica is the largest-volume specialty silica. Although production is largely regional, ownership is largely concentrated, with a relatively small number of companies accounting for the bulk of global capacity. Technology and raw material position are major factors. Asia (excluding Japan) is the fastest-growing market, primarily to serve shoe and tire markets. Capacity has expanded to meet growing demand, and further expansion is probable. Although there are a number of small-scale producers in China and India, most world-scale plants are owned by the major world producers either alone or via joint venture. The primary markets for precipitated silica are as a specialty filler and carrier.
A small number of major companies, a significant number of regional second-tier companies, and numerous smaller companies (primarily located in Asia) serve the world silica gel market. Technology is an important factor in higher-value markets, such as food and health care products and flattening agents for coatings, but is currently less important in some commodity adsorbent/desiccant markets. As is the case for other specialty silicas, Asia excluding Japan, is the fastest-growing market as its industrial base continues to grow. Capacity is expanding to meet demand and low-cost imports from China have had a major impact on markets in North America and Western Europe.
Fumed silica products command the highest prices of the major specialty silicas. The business is worldwide and is highly concentrated. Technology is tightly held and constitutes a major barrier to entry. The customer base for the major end use, the silicone elastomer market, is small—a few major silicone producers dominate global silicone elastomer capacity. As a result, supplier/customer relationships are close, with production at the customer’s site in some instances.
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