Perlite deposits and market trends in North America

摘要

Commercial pcrlite is weathered volcanic glass (obsidian, perlite, pitchstone) that expands. Rapid heating to c. 600 -800°C in special furnaces softens the volcanic glass, causing its contained water to form steam bubbles. The bubbly molten glass, when cooled rapidly, forms cellular foam with uses in construction, horticulture, filtration and fillers. This expansion or 'popping' of the periite yields particle densities of ≤190kg/m~3 compared to about 1920 kg/m~3 before expansion. In 1999, crude perlite mined worldwide was about 2.1 Mt. Major producers outside North America were Greece 425000t, China 400000t, Japan 200000t, Turkey 160000t, Hungary 80000t and Mexico 60000t. Several other countries also produced perlite. The western USA (Arizona, California, Nevada, Oregon, Utah, and New Mexico) led North American producers with 726 000t valued at $21.8 million or $30/t in 1999. Mexico produced perlite in Chihuahua, Puebla, Sonora, and Durango, all for domestic use. Canada has no recent production from deposits in British Columbia. All perlite is imported from Greece or the USA Expanded perlite was valued at an average of about $200/t in the USA where construction uses accounted for 71% of expanded perlite domestic sales. Horticultural aggregate accounted for 10%, filter aids 9%, fillers 7% and others 3%. New, reopened or expanded North American operations, along with imports, will increase supply to meet growing demand, thus eliminating the recent North American perlite shortages in certain grades. Imports from Greece (by Silver and Baryte) control markets in eastern North America. Import and exports throughout the Pacific Rim, both from North America and China, are altering West Coast markets.