TMA goes commercial Amoco Chemicals is stepping up its capacity for trimellitic anhydride. The sole supplier of TMA, Amoco plans to build a new 50 million pound-a-year plant at Joliet, 111., to make the intermediate. The construction contract has not been awarded. Completion is slated for 1968. Amoco has been supplying TMA from a semicommercial unit built in 1962. The capacity of this unit, only a few million pounds a year, is being expanded to help meet customer needs until the full-scale plant is on stream. Demand for the compound, which is the anhydride of 1,2,4-benzene tricarboxylic acid, has climbed steadily over the past few years. Last year, for instance, sales of trimellitic acid ester plasticizers hit 1.98 million pounds, compared to 1.34 million pounds in 1964, according to the U.S. Tariff Commission. TMA is also finding use in alkyd resins for watersoluble and conventional coatings, epoxy curing agents, polyester imides, polyamide imides, and other chemical intermediates. The raw material for making trimellitic anhydride is pseudocumene (1,2,4-trimethyl benzene). Amoco has been buying pseudocumene on the merchant market and says it has no plans to make it. Producers of the chemical include Hess Oil & Chemical, En jay Chemical, and Phillips Petroleum. Pseudocumene is recovered by superfractionating the C 9 aromatics in a refinery. It is converted to TMA via an oxidation process using air and acetic acid. The new Joliet plant will use a patented oxidation method developed by Amoco and MidCentury Corp., also a subsidiary of Standard Oil (Ind.). Pseudocumene can be isomerized to mesitylene for producing trimesic acid, which Amoco is also producing at Joliet. It has been offering trimesic acid in experimental quantities for use in alkyd resins, plasticizers, molding resins, and resin intermediates.
Niobium deposit found in Canada A large deposit of niobium, a metal valuable for alloying steel, has been discovered in Canada by a group of companies headed by Imperial Oil, Ltd. The deposit is in the James Bay lowlands, 400 miles north of Toronto. It contains 40 million tons of crude pyrochlore ore—a complex of sodium, calcium, and niobium oxides. The discovery comes at a time when U.S. consumption of the metal, largely as ferroniobium, is growing. (By con34 C&EN OCT. 17, 1966
Electron beam furnace for Nb No real markets
trast, use of the pure metal is dropping. ) Ferroniobium consumption has risen from 1.74 million pounds in 1961 to 2.75 million pounds last year, the U.S. Bureau of Mines shows. A. W. Stollery, president of Consolidated Morrison Explorations, Ltd., one of the companies in the group with Imperial Oil, says that the new deposit apparently contains 0.52% niobium pentoxide. Some sections run as high as 0.80%, he adds. Toronto-based Imperial Oil, which is 69% owned by Standard Oil Co. (N.J.), is paying for exploration of the deposit. The company will own 60% of the find as soon as it spends $1 million on the project. Consolidated Morrison, which is handling the exploration, will then own 25.9%. Two other concerns and the vendor of the property will own the rest. Mr. Stollery says metallurgical tests show that high-grade concentrate can be made from the ore. Exploration is continuing, and exploitation of the deposit could start within a year. Canada is already one of the major U.S. sources for niobium concentrate. Last year, 1.9 million pounds of Canadian pyrochlore concentrate, containing approximately 55% niobium pentoxide and costing about $1.10 per pound, were imported. Most of it came from St. Lawrence Columbium & Metals Corp., which mines at Oka (near Montreal). Another 600,000 pounds of pyrochlore concentrate were imported from Brazil last year. The other major niobium ore is columbite, which also contains tantalum, a metal related chemically to niobium. U.S. imports of columbite concentrate were 2.5 million pounds in 1965, including 2.1 million pounds from Nigeria. This concentrate contains about 56% niobium and tantalum
pentoxides and costs about 85 cents per pound. Total U.S. 1965 imports of 5.0 million pounds of columbite concentrate compare with 2.8 million pounds five years ago. Niobium is not mined in the U.S. Ferroniobium, at about $3.00 per pound of contained niobium, is the only really established outlet for the metal. It is made domestically by Kawecki Chemical, Molybdenum Corp. of America, Reading Alloy, Shield Alloy, Union Carbide, and Vanadium Corp. of America. Added to stainless steel, ferroniobium prevents precipitation of carbide at high temperature. Added to some other steel in trace amounts, the alloy substantially boosts tensile strength. Use of ferroniobium in the U.S., as measured by contained niobium, has spurted from 1.05 million pounds in 1961 to 2.20 million pounds last year. One factor behind the increase is the growing use of the alloy in lower grade steels. But U.S. production of the pure metal has fallen from about 300,000 pounds in 1960 to 95,000 pounds in 1964. Last year's figures are not available. Current U.S. producers are Fansteel, Kawecki, Kennametal, Union Carbide, and Wah Chang. The metal has many excellent properties—it has good high-temperature strength, workability, and chemical resistance, and some properties that make it suitable for nuclear applications; but no real markets have developed yet. The price of the metal is about $40 per pound.
TVA de-emphasizes sulfur Higher sulfur prices and more use of liquid or suspension fertilizers proved major influences on the Tennessee Valley Authority's sixth demonstration of new developments in fertilizer technology. Special emphasis was on processes using a minimum of sulfur to make fertilizers containing phosphorus; on suspension fertilizers with low acidity and high P 2 0 5 solubility; and on methods to add secondary nutrientssuch as sulfur, magnesium, boron, and zinc—to suspensions. Granular fertilizers were by no means forgotten at this demonstration, latest in a series held every two or three years. TVA had in full swing its new (operating only since November 1965) demonstration plant to make granular fertilizers by any one of three processes. A TVA rotary drum ammoniator-granulator was used to make a nitric phosphate. On a pilot-plant scale, TVA showed its latest technology for pan granulation of urea. Large ammonia plants and lowercost nitric acid together with prospects
of still higher sulfur prices are behind TVA's interest in nitric phosphate processes. TVA's efforts, still largely on a bench scale, seek to improve nitric phosphate processes, most common of which is the Odda (named after a Swedish firm which did some of the early development). In the Odda process, ground phosphate rock is treated with nitric acid, the slurry cooled, and calcium nitrate filtered off. The filtrate is ammoniated and processed to a granular product in a conventional TVA ammonia tiongranulation system. The calcium nitrate is converted to ammonium nitrate and precipitated calcium carbonate with ammonia and carbon dioxide. The main difficulties with this process for commercial use are that about a third of the calcium remains in the product and about half of the P 2 0 5 is insoluble. The calcium lowers the fertilizer grade and limits the water solubility of P 2 0 5 . To overcome these difficulties, TVA has brushed off and is modifying an old process—first patented in 1930— to remove the calcium. The process has two basic steps. First, ammonium sulfate solution is added to the phosphate rock-nitric acid mixture; the resulting calcium sulfate precipitate is filtered off and washed with more ammonium sulfate solution. Second, the calcium sulfate is reacted with ammonia and carbon dioxide, calcium carbonate filtered off, and the ammonium sulfate solution regenerated. In batch laboratory tests, TVA
chemists can remove 92% of the calcium and get a product of mostly ammonium nitrate and ammonium phosphates. The P 2 0 5 is 100% citrate soluble (a measure of its potential availability in soils) and about 90% water soluble. The maximum loss of sulfur as sulfate by this process is 26 pounds per ton of product, based on laboratory experiments. This sulfur can be supplied as sulfuric acid or gypsum, for example. Suspension fertilizers continue to attract attention. But initial acidity of suspension fertilizers is high. If acidity is reduced with ammonia, dicalcium phosphate present reverts to fluorapatite, practically the same mineral as mined. To inhibit this reversion, TVA adds a polyphosphate such as an 11-37-0 grade of ammoniated polyphosphoric acid. If 15 to 20% of the P 2 0 5 is added as 11-37-0, no reversion occurs for 45 days. TVA has also found that the polyphosphate must be added during ammoniation when the pH is 2.0 to 2.5, and nearly all the P 2 0 5 precipitated as dicalcium phosphate. Micro- and secondary nutrients can be added to suspension fertilizers within one major limitation—viscosity. Large quantities can be put into suspensions, in contrast with liquids where salting out may be a problem as the temperature decreases. Clay, 2 to 3 % , is added to carry larger-volume secondary nutrients such as sulfur (10 or 20%) and magnesium (3%). Viscosities of the suspensions containing sulfur roughly double after
TVA pan granulator Latest technology for granulation urea
standing a week at 80° F. Viscosities of suspensions containing magnesium triple (from a few per cent), depending on the magnesium compound used. Some suspensions containing magnesium are thixotropic, but pourable.
Photosynthesis—path to food The idea of producing more and better agricultural products by tinkering with the extremely complex mechanisms which control photosynthesis is today little more than a dream. But the eventual importance of such an approach to help relieve the world's food problems must not be underrated, according to the University of California's Dr. James A. Bassham. However, much research remains to be done to bring the dream to reality, he said at the Symposium on Photosynthesis, held to highlight the dedication of International Minerals & Chemical's -S6.5 million Growth Science Center in Libertyville, 111. The Berkeley scientist says that leaves which can be eaten by people may become a much more important crop in the future. For instance, vast crops of jungle foliage could become key food sources if chemical sprays that would enrich leaves in fats and protein can be developed. Dr. Bassham points out that photosynthesis produces not only sugar and carbohydrates but also fats, proteins, fatty acids, and other compounds. Current and future work on the mechanism which controls the distribution of these products—and on ways to manipulate this mechanism—is providing the basis for a new era in agricultural research. So far, a few chemicals, such as methyl octanoate, have been found which reversibly inhibit photosynthesis by deactivating certain enzymes (much as darkness does). Dr. Bassham predicts that lower levels of such inhibitors may bring about "interesting" changes in the quality of photosynthetic products. To date, the pathways from carbon dioxide to the various products have at least been outlined. The variety of regulatory mechanisms have been sketched in. But many complicating factors remain. For instance, he told the symposium of recent work in his Berkeley laboratory on the interaction between photosynthesis and glycolysis—the nonphotosynthetic breakdown of sugars to metabolic intermediates. This work has led to some indications of the role of diffusion of intermediates in the control mechanism of photosynthesis. Earlier studies have shown that OCT. 17, 1966 C&EN 35
