Lead & Zinc

Lead And Zinc Production

Deposits of galena, the lead mineral commonly associated with zinc and silver, occur in Blanco, Brewster, Burnet, Gillespie, and Hudspeth counties. Zinc comes primarily from the mineral sphalerite, or zinc sulfide. Lead and zinc occur with other minerals in Presidio, Hudspeth, Culberson, and Brewster counties, and there are deposits of lead ore in Blanco and Burnet counties and in the Llano area. Some zinc mineralization can be found in lead deposits of the Cambrian rocks in Central Texas, and zinc sulfide deposits occur with other minerals in the salt domes of the Gulf Coastal Plains. Both lead and zinc are usually by-products of silver.

In 1901 and 1902 a small smelter at Shafter produced lead from ore obtained at the Chinati Mine in Presidio County. Between 1911 and 1917 mines in the Trans-Pecos produced small quantities of zinc, and in 1915 and 1916 there was some lead production in connection with silver in that region. Shipments of zinc carbonate were made from the Chinati and Montezuma Mines in Presidio County during the same period. In 1930 twenty-nine tons of lead concentrates was produced from ore mined on Silver Creek in western Burnet County. Total zinc production in the state up to 1933 was 1,488,474 pounds, almost all of which had come from the Bonanza and Alice Ray Mines in the Quitman Mountains of Hudspeth County. Texas produced 410,000 pounds of lead in 1940, but only 362,000 pounds two years later. The total production of lead in the state from 1885 to 1944 was 4,788 short tons. Lead and zinc produced in Texas has been smelted at El Paso and at Dumas, Moore County, where a large lead smelter processes lead ores from several western states.

Between 1885 and 1952 total lead production in the state amounted to 5,443 short tons, and total zinc production amounted to 837 short tons. Some additional lead had been produced as a by-product of silver mining from the Presidio Mine in Presidio County and the Bird Mine in Brewster County, and additional zinc production had come from the Buck Prospect in the Apache Mountains of Culberson County.

After 1952 no lead or zinc was mined in Texas. In the 1960s and early 1970s, however, primary lead smelters at Dallas and El Paso processed ore and concentrates from western states and Mexico. In addition, seven secondary smelters, three each in Houston and Dallas and one in Fort Worth, treated scrap material, which supplied 60 percent of total United States lead production.

Zinc production in Texas likewise depended upon imported ore. In the mid-1950s, zinc smelting was one of the state's leading metal industries. The American Smelting and Refining Company (ASARCO) plant at Corpus Christi was one of five in the nation using the electrolytic process, while plants at Amarillo and Dumas smelted zinc by the horizontal-retort method. Texas plants also produced such by-products as sulfuric acid, cadmium, and zinc sulfate crystals. The El Paso smelter produced 40,000 tons of zinc oxide in 1955, and by 1961 the Corpus Christi plant supplied 18 percent of the nation's cadmium.

In 1957 rapidly mounting domestic stocks curtailed zinc production. In 1961, however, Texas produced 191,053 tons out of a national total of 846,795 tons, to lead the nation in slab zinc production. That year Texas zinc-smelting facilities expanded to five electrolytic, seven horizontal-retort, and four continuous vertical-retort smelters, and by 1964 the Corpus Christi plant alone had an annual capacity of 100,000 tons.

In the 1970s, New Mississippi Valley-type lead-zinc mineralization was discovered in central and western Gillespie County, thus extending known lead mineralization thirty-one miles west of the Llano Uplift. Lead continued to be produced from domestic and imported ores and concentrates from Mexico and other states at the ASARCO smelter in El Paso, while the American Zinc Company operated a retort smelter at Dumas. The ASARCO Amarillo retort smelter reported lower production due to a labor shortage, however, and the Corpus Christi electrolytic zinc plant suffered damage from Hurricane Celia. In 1975 ASARCO closed its Amarillo zinc smelter, one of two in the state, because of air-pollution problems; at the same time it was involved with public claims of lead poisoning at other Texas facilities. On the basis of a 1972 judgment, the company had agreed to pay medical expenses for children living near its El Paso smelter allegedly suffering from lead poisoning. Zinc production was sharply lower because of a drop in metal demand. By the end of the decade, ASARCO had completed a modernized copper-lead-zinc plant at El Paso and had received an extension from the Texas Air Control Board for permanently reducing its ground-level concentration of sulfur dioxide at the El Paso smelter to a permissible level.

In the 1980s the ASARCO smelter on El Paso's west side produced an environmental hazard when plans were made to convert a natural gas furnace there to coal. The community objected, despite the company's major investment in pollution-control equipment after 1967. A strike in 1981 interrupted raw-materials shipments from El Paso to ASARCO's Corpus Christi zinc refinery, where crude zinc oxide was recovered by the fuming of lead smelter slag. Operating at a reduced rate, the refinery produced about 160 tons a day of refined zinc from purchased ore concentrates. ASARCO began modernization at its Corpus Christi zinc refinery, but weak demand and downtrends in price continued in the early 1980s. As a result, the company suspended operations at its El Paso lead smelter and zinc fuming plant and its operations in Corpus Christi. In the 1990s, Tejas Resources broke ground for a plant in Terrell, Texas, capable of recycling 3.25 million batteries a year without loss of emissions and contaminants. The plant was expected to produce 25,000 short tons of lead and other materials.

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