I Key Chemicals H 2 S0 4
Sulfuric acid Sulfuric acid, the largest-volume product acid for subsequent use in various of the U.S. chemical industry, has un- phosphate fertilizers. Relatively little of dergone little change in its supply/ this phosphoric acid is made using • Capacity up modestly demand situation over the past two smelter acid. This use, about two thirds of all years of generally better business con• Prices low ditions. Production has moved up. So phosphoric acid consumption in the has production capacity. Unfortunately U.S., largely determines the fate of the for producers, prices have about re- sulfuric acid industry. (More details on mained the same even though cost of phosphoric are contained in the section on phosphoric acid that follows.) This production has increased. PRODUCTION/CAPACITY Specifically, production of sulfuric year's phosphate fertilizer production, acid in 1977 increased about 1.7 million also running at a lower growth rate than Millions of tons, 100% H2SO. tons, or 5% over 1976. This growth rate, in 1977, will account for most of the 60 higher than the rate expected for 1978, lower growth in sulfuric acid produc• Production Capacity may prove above average for the next tion. In this largest outlet, sulfuric acid few years as well. This year, production of sulfuric acid probably will be up less acidifies phosphate rock to make 50 than 3.5%, or substantially under last phosphoric acid. By-product gypsum, year's gain. If the slowdown in economic calcium sulfate, is discarded in enorgrowth forecast for 1978 occurs fol- mous piles adjacent to the plants. However, smaller quantities of sullowing the scenario of most economists, 40 production of sulfuric acid probably will furic acid are used in making another fall to between 36.5 million and 37 mil- fertilizer material, ammonium sulfate. This ammonium sulfate competes with lion tons. No problems are likely in meeting ammonium sulfate coproduced with demand during 1978. In-place capacity other chemicals, such as caprolactam at the beginning of the year totaled some and some acrylic acids and esters, and 55 million tons. More capacity will be with ammonium sulfate resulting from coming on stream during the year, too, recovery of ammonia produced in coal making expected demand increases coking. Fertilizer demand hence has a coneven easier to supply. Excluding new capacity, existing plants will need to run trolling influence on sulfuric acid pro1976 1977 1978 at about only two thirds of design ca- duction. Some of the largest sulfuric acid HOW MADE units in the U.S. have their output dedipacity. Certain units undoubtedly will be op- cated entirely to phosphate rock acidiBurning elemental sulfur, subsequent erated at substantially higher rates dur- fication. As a result, when demand for oxidation, and reaction with water; ing much of the year. But others, espe- phosphate fertilizers falls off for any recovery from metal smelting cially those whose feedstock is sulfur reason, substantial acid capacity often dioxide vented from smelters, are likely is shut down. Efforts certainly are made to be run at very low levels of design by the sulfuric acid plant operators to MAJOR END USES sell some production to other uses. capacities. Fertilizers 65 % ; petroleum refining The smelter acid situation provides a Usually, the logistics defeat these efforts. At these times, one expedient for small ray of hope to producers of sulfu5%; manufacture of metals and operators is to carry out plant mainteric acid based on elemental sulfur. Dederivatives 5 % ; manufacture of nance with the objective of enabling pending on the viewpoint, the current chemicals 5% plants to run at high rates without interoversupply of copper and other metals ruptions when demand for fertilizers is can be favorable or unfavorable to some FOREIGN TRADE high. sulfuric acid consumers. If a plant using The nonfertilizer uses of sulfuric acid sulfuric acid depends on smelter acid, its Exports and imports negligible operators can face serious problems as run throughout manufacturing. For exthe result of a smelter cutback or shut- ample, many kinds of chemicals require down. Chances are that another source sulfuric acid in their manufacturing PRICES of sulfuric acid is farther away than the processes. None of these other uses, in Vary widely. Nonsmelter acid smelter. This means that transportation terms of individual products, takes more contracts—$45 to $50 per ton at costs would be higher. And, since than about 5% of sulfuric acid producplant; smelter and spot—as much as smelter acid generally has a lower tion. $20 per ton lower These other uses, up or down, still selling price than does other sulfuric acid, the total cost increase would be hold minor-league positions compared to fertilizers. This year and for many even higher. COMMERCIAL VALUE Sulfuric acid production at smelters years hence, fertilizer will control sulI $1.5 billion for total production, 1977 isn't important, however, to sulfuric furic acid's fortunes. At present, that's acid's largest use—making phosphoric not a desirable dependence.
• Demand growth slower
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March 27, 1978 C&EN
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