late existing chemical hazards. Rauch's organization, the Environ mental Defense Fund, asked the E P A a year and a half ago to regulate asbes tos in schools and other public build ings. So far there has been no such regulation, although E P A has request ed a voluntary compliance effort. "This is the overregulation you're hearing about from the Monsanto Co. in their advertising campaign," said Rauch. "I quite honestly get rather con cerned when I hear this very loose talk about regulation, as if it was some hazy blob out on the horizon, with no benefits, no direction, except to em ploy a bunch of shiftless bureaucrats," he continued. "Any of you who don't believe t h a t the threat from private li ability actions is a serious one should contact the Johns-Manville Co. right now." T h e very existence of the com pany is in jeopardy because of actions
brought by workers who had handled asbestos-filled insulation products. "Our thesis is that, despite all the rhetoric and despite all the advertis ing, regulation, when not carried to ex cess (and obviously we can disagree about t h a t ) , is probably the best in surance policy t h a t industry is carry ing today," Rauch said. He appealed to businesspeople to look beyond the short term to the dangers t h a t can be caused by a failure to regulate. Rauch agrees t h a t the regulatory structure can certainly be improved, b u t be lieves t h a t it provides some very es sential safeguards to our society. In addition to this yearly confer ence, Government Institutes sponsors seminars on environmental laws and regulations, among other activities. For details on these activities contact: Government Institutes, Inc., 4733 Bethesda Ave., N.W., Washington, D.C. 20014.
Analysis in the Cement Industry T h e Louisville Cement Co. of Speed, Ind., celebrates its 150th anni versary this year. Like other manufac turers of this essential product, Louis ville Cement is vitally dependent upon analytical chemistry for the monitor ing of raw materials and intermediate and final products. Cement is a mixture of several chemical compounds combined in pre cise proportion. Most of the cement manufactured today is Portland ce ment, which largely replaced the older " n a t u r a l " cement early in this cen tury. T h e process to manufacture Port land cement begins in the quarry, where samples from core drilling and prospecting are obtained and sent to the laboratory for chemical analysis. Samples of clay, limestone, and shale
from the quarry are analyzed for im p o r t a n t components by wet chemical methods or by X-ray spectrometry. T h e cement manufacturer is inter ested primarily in Ca, Si, Fe, and Al, though elements such as Mg, Na, K, and S are usually present as well, and must frequently be determined. In ad dition, trace concentrations of ele ments such as Ti, Mn, and Ρ in the core drillings are determined by atom ic absorption spectrometry. After quarrying, the raw materials are proportioned. A typical mixture might be 85% limestone, 12% clay, and a few percent boiler slag, iron ore, or fly ash. This mixture constitutes what is known as the kiln feed, and its com position must be controlled to rather close tolerances. Analysis is also of critical importance here, and Louis
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ville Cement is presently using a Phil ips PW1600 X-ray spectrometer for the analytical workload. Louisville Cement uses a kiln with a suspension preheater to conserve en ergy. It is more efficient in recovering heat than the old dry process kiln, b u t it is also more demanding. Introduc tion of the suspension preheater kiln necessitated more frequent and more rapid analytical testing a t more points in the system, because of higher throughput and shorter residence times compared to the older system. T h e suspension preheater operates more efficiently when the composition of the kiln feed is accurately and uni formly controlled, and temperature profiles are held within critical ranges. T h e need for rapid analytical infor mation is underscored when you con sider the fact t h a t the suspension pre heater kiln handles a load of about 3000 tons/d. T h e X-ray spectrometer requires 40 s from sample loading to analytical result, compared to a turn around time of 3-4 h by wet chemical methods, which are nevertheless still used in an emergency. Testing is done around the clock by plant personnel earning an hourly wage and capable of unsupervised op eration. T h e X-ray simultaneous spec trometer at Louisville can analyze for 11 elements, and is operated and con trolled by a computer. T h e computer software makes the necessary analyti cal programming calibration and all requisite calculations. Test results are then printed out for immediate feed back to process control. T h e raw materials in the kiln are first calcined, i.e., the CO2 is driven off. T h e n the temperature is brought u p to 2600-2700 °F., at which temper ature the Fe and Al begin to flux with the Ca and Si present, until they form what is known as "clinker," fused ma terial in chunks the size of walnuts. T h e clinker spills out white-hot into a cooler, and after it cools it is analyzed for its chemical composition. X-ray spectrometry is also used for analyses at this stage, with wet chemical meth ods as a back-up in case of instrumen tal problems. In t h e finishing d e p a r t m e n t t h e clinker is ground to a powder, which is analyzed once more to ensure t h a t it meets specifications. It is then sold to manufacturers of ready-mix concrete, who mix the cement with sand, gravel, and water to make concrete. Cement is t h e flour and concrete is the bread. T h u s , analytical chemistry plays an essential role in the modern cement industry. As David P . Elliott, chief op erating chemist at Louisville Cement puts its, "You start testing in the quarry, and you don't really quit until the cement is ready to be loaded into the customer'3 truck."
