Annual Review of Illinois Industrial Minerals Completed
Geologists at the Illinois State Geological Survey (ISGS) completed the annual review of Illinois industrial minerals for the Society of Mining Engineers' Mining Engineering magazine and the U.S. Geological Survey's (USGS) Minerals Yearbook. Two extended abstracts were also published in the abstract volume of the 44th Forum on the Geology of Industrial Minerals.
Of the industrial minerals mined or manufactured in Illinois, those that have the highest value include crushed stone, cement, sand and gravel, and industrial sand. Crushed stone and sand and gravel aggregate materials combined continue to account for more than 60% of the value of Illinois' nonfuel industrial minerals. Dolomite, mined from the Silurian and Ordovician carbonates in northern Illinois, accounted for most of the total stone production.
In terms of value, industrial minerals continue to be Illinois' leading mineral resource commodities, totaling $1.22 billion. According to the USGS mineral industry profile, Illinois ranked 16th among the 50 states in total value of nonfuel mineral production. By value, crushed stone was the state's leading industrial mineral, accounting for about 47% ($573 million) of the total, followed by portland cement, 25% ($308 million); construction sand and gravel, about 14% ($176 million); and industrial sand, about 8% ($102 million). Lime, fuller's earth (absorbent clay), tripoli (microcrystalline silica), and other nonfuel minerals, in decreasing order, accounted for most of the remaining 5% ($63 million). Economic analysis indicates that, because of their large impact on construction and transportation infrastructure, every dollar=s worth of industrial minerals consumed in Illinois contributes $550 directly and indirectly to Illinois' gross state product.
Road maintenance and improvement are major sources of demand for the state's crushed stone, sand and gravel aggregate, and cement. According to the Illinois Department of Transportation, Illinois has the third-largest network of state and local roads and the sixth-largest interstate highway system in the country. The state also has more than 26,000 bridges, 8,227 of which are in the state highway system, which is heavily used. A significant number of bridges need repair or replacement, as do many stretches of the interstate highway system and many state and secondary highways and roads. Large amounts of construction aggregates are required to keep interstate highways in top condition, maintain major highways, and improve congested urban and rural highways.
Illinois is experiencing a dramatic increase in demand for high-calcium limestone, mainly in response to environmental regulations set by state and federal governments that made it necessary for coal-fired power plants to be equipped with limestone-based scrubber systems to reduce sulfur dioxide (SO2) and mercury emissions. Stringent pollution control requirements have accelerated installation of limestone-based desulfurization (FGD) systems in coal-fired power plants. This trend toward increasing numbers of FGD units is expected to continue. Because of the importance of high-calcium limestone as a scrubbing agent, it is essential to address issues associated with the transport, availability, and suitability of high-calcium limestone resources for use in FGD power plants. Nearby sources of suitable limestone raw material must be found to feed existing and new scrubber installations and to aid in the selection of proper resources for desulfurization systems in the future. The ISGS is continuing to map and characterize Illinois high-calcium limestone resources that are suitable for controlling sulfur dioxide and mercury emission in coal-fired power plants.