and more sulfuric acid are reacted with phosphate rock to give a 0-30-10 mixture of phosphoric acid and monobasic potassium phosphate, along with gypsum (calcium sulfate) and hydrogen fluoride. If silica is added as a pollution control measure then solid potassium silicofluoride (K 2 SiF 6 ) replaces gaseous HF in the product mix. Subsequently, the mixture of K H 2 P 0 4 and H3PO4 can be ammoniated to give an 8-48-16 fertilizer, reacted with more rock to make a 0-45-15 material, or subjected to methanolic precipitation. To produce high-quality phosphoric acid, usually called furnace grade because the acid is made by "burning" phosphorus produced in an electric furnace, the wet-process phosphoric acid industry is looking at many kinds of organic treatments and systems. Solvent extraction is being used in Israel, for example. Pennzoil, however, is developing methanolic precipitation at its Hanford plant. The 0-30-10 filtrate from the acidulation step is clarified and partially evaporated to a dissolved solids content of 50 to 60%, depending on the impurities present. Methanol is added, and solid agglomerates with an almost crystalline appearance separate almost immediately. The slurry is centrifuged and washed to remove methanol and most of the occluded phosphoric acid. The solid material—fertilizer-grade KH2PO4, called Marina Salt by Goulding and K-Phos by Pennzoil—can be treated further to make various fertilizer materials. The clear methanolic filtrate is stripped of methanol to yield a phosphoric acid stream of about 0-54-2. This material can be used as such in liquid fertilizers, evaporated to a 0-72-3 material, or made into dicalcium phosphate, detergent phosphate materials, or food-grade 0-54-0 (using ion exchange). The wash liquor and methanol are recycled. To produce polyphosphates, the 0-47-31 plant food ratio of the solid K-Phos material must be adjusted to a more favorable 0-50-40 ratio. This can be done by removing P 2 0 5 or adding K 2 0 . Both routes are acceptable for detergent phosphates, but too expensive for fertilizers. Pennzoil, Mr. Drechsel says, has an undisclosed scheme for changing the ratio that requires no additional processing. Nor does it require an increase in the value of K 2 0 or P2O5. Polymers for fertilizer use are best made from a mixture of mono- and dibasic potassium phosphates. The monobasic material controls the size (molecular weight) of the polymer and its corresponding water solubility. Controlling the concentration of the two compounds in the feed can give the desired product composition without high costs. Costs of making potassium phosphates using the bisulfate route become more favorable as energy costs rise. The value of sulfuric acid is of little significance since it is required whatever the route. The important considera18
C&ENSept. 10, 1973
fied by environmental reasons alone, Mr. Drechsel says, it can be reduced through elimination of K 2 0 loss and recovery of 80 to 90% of fluorine in the feed. Processing costs to separate the 0-47-31 K-Phos from the filtrate mixture using methanolic precipitation are estimated by Mr. Drechsel at $10 to $12 per ton as P2O5. If all the costs were allocated to the pure phosphoric acid coproduct, its cost could increase by $25 per ton as P2O5. Even now the price difference between wet-process and furnace acids runs about $50 per ton as P2O5. Environmental concerns and energy costs could cause this differential to jump in 1974-75. Hence, Pennzoil believes that a methanolic precipitation facility could be profitable whether or not potassium phosphates are produced. Considering all of the nonprocessing and environmental cost factors, timing for new technology for high-analysis fertilizers seems right. And cost effects could make coproducts from potassium phosphates production more important than the fertilizers themselves.
tion is the HC1 price required to keep the value of K 2 0 in the product unchanged. For example, if total conversion cost is $25 a ton for K 2 0 , and conversion of 0.5 mole of K 2 0 produces a mole of HC1, the price of $32.30 a ton for HC1 is needed. Some estimates place chlorine at $50 a ton in 1975. Processing costs to make chlorine from HC1 by one process are estimated at $15 to $20 a ton. Thus HC1 would be worth that much less than chlorine, or $30 to $35 a ton. Pennzoil has a simple, but still proprietary, treatment that will give potassium bisulfate nearly the same handling, shipping, and storage characteristics of other fertilizer materials. This implies that HC1 could be produced at one location, while potassium phosphates could be produced at one or more other locations, thereby reducing freight costs. Another cost improvement involves the fluorine pollution abatement scheme, in which loss of K 2 0 values in the K 2 SiF 6 is 18.2% on a stoichiometric basis. Although the cost could be justi-
Process decolors kraft mill effluent ENVIRONMENTAL—A new onestep process for decoloration of kraft mill bleach effluents has been developed by Rohm and Haas research scientists. It is based on the use of a new polymeric adsorbent, Amberlite XAD-8, in the form of 20- to 60-mesh spherical beads. XAD-8 is composed of a highly cross-linked, hydrophilic, porous polymer. With no ion exchange groups, it functions as a true adsorbent.
According to Dr. David C. Kennedy, of Rohm and Haas' research division, decoloration of bleach effluents is among the most difficult waste disposal problems in the paper industry. Kraft mills generate 10 million to 20 million gallons per day of colored bleach effluent. There is also a moderately high biochemical oxygen demand (BOD) of 100 to 200 p.p.m. and significant quantities of suspended solids in the effluent. Most
New process tackles paper mill effl uent To paper machines White pulp Bleaching process
B,each
Highly colored spent bleaching liquor
Brown pulp Borrowed caustic régénérant Wood chips
Pulping process
Highly colored spent régénérant
Organic-laden black liquor Caustic recovery furnace Burned organics Discharge to air Carbon dioxide and water
Recovered molten caustic
Amberlite XAD-8 decolorizing process Decolorized bleaching liquor Discharge to stream 85% decolorized 40% BOD removed
of the disposal problems can be handled efficiently, but the color problem is still a costly one. The color components are by-products of lignin oxidation and degradation. The most common decoloration process used at present, Dr. Kennedy says, is the "massive-lime" process, which flocculates the color components. A "mini-lime" variation also is used. A third process has been introduced recently in Sweden which employs ion exchange decoloration. All three processes, Dr. Kennedy claims, suffer from several drawbacks. One is that the final degree of decoloration is limited. Also, they require high capital and operating costs, and the large quantities of lime necessitate special handling techniques. In the new Rohm and Haas process, acidic bleach effluent is passed through a bed of the adsorbent that removes colorants and other organics. The adsorbent is periodically regenerated with a caustic process stream that removes the colorants and concentrates them for subsequent combustion in the mill's caustic recovery furnace. Because Amberlite XAD-8 is not an ion exchange resin, it will not remove chloride ions from the bleach effluent. Consequently, there is no danger of increasing the chloride level of the processing loop, a major problem in some processes. The new process is capable of treating all or part of the bleach effluent as long as it remains acidic. It can reduce color of the total bleach effluent by 90 to 95%. Concurrently, BOD can be reduced by up to 40% and the chemical oxygen demand can be reduced by up to 60%. Economic analysis of a test at a large pulp mill indicates that the new process is competitive with existing processes. A speculative cost comparison made by Dr. Kennedy suggests that the Rohm and Haas process can be operated at costs from 55 to 64 cents per ton of pulp. This compares with $1.86 for the massive-lime process, $1.26 for the mini-lime process, and 92 cents to $1.85 for the ion exchange process. Capital cost for an 800 ton-per-day plant providing 72% total bleach decoloration would be $710,000 to $920,000 for the new process. The corresponding cost for the massive-lime process would be $2.36 million, for the mini-lime process $900,000, and for the ion exchange process $1.8 million.
Federal panel reports on hydrogen FUEL—The possible ultimate depletion of fossil fuels has prompted numerous investigations into the potential of other sources of energy. The most comprehensive of these was begun in 1972 by the Energy R&D Goals Committee of the Federal Council on Science and Technology.
Panel indicates R&D goals for nonfossil fuel industry Short term (by 1985) • Development and demonstration of methanol from coal as an automotive fuel. • Development and demonstration of hydrogen produced from coal for use in the industrial sector both as a chemical and a fuel. • Development and demonstration of hydrogen as an energy storage medium for electric utilities use in supplying peak power demands. ·. Development and demonstration of the production of gaseous and liquid fuels from urban and agricultural waste products. Long term (after 1985) • Use of hydrogen as a transportation fuel, particularly for aircraft and specialized ground vehicles. • Hydrogen production investigations. • Long-distance transmission and bulk storage of hydrogen. • Public safety studies. The study involved 11 separate panels, each looking into one aspect of the national energy problem. The chairman of the panel on hydrogen and synthetic fuels, Dr. John W. Michel of Oak Ridge National Laboratory, has summarized the panel's findings and sketched its recommendations for research and development. The panel's main conclusion was that synthetic fuels, particularly hydrogen, can have a significant and beneficial effect over the long term. The main obstacles to use of hydrogen as a universal fuel are high cost relative to present fuels and unresolved problems of handling a low-density or cryogenic fluid. The panel believes that safety considerations will present no serious obstacle to use of hydrogen. According to Dr. Michel, the panel had no doubt that most of the economic problems can be resolved by appropriate R&D programs. The recommendations of the panel were divided into two categories, those that could have major impact on the nation before 1985 and those after 1985. Assuming a reasonable funding level, the panel projects that its programs would require up to five years of effort in most cases. What constitutes a reasonable funding level has not been made public at this time. A methanol R&D program would establish the economics and technology of methanol production from coal and lignite, as well as the end uses in automobiles. Because auto transport represents the biggest single use of petroleum, successful implementation of the program could have significant effects on oil imports and on air pollution. Several hydrogen utilization programs also appear to have near-term viability and would relieve the demand for natu-
ral gas and petroleum. The panel estimates that a five- to 10-year R&D program would be required to establish the feasibility of using hydrogen as a transportation fuel. This program would place particular emphasis on fuel tankage and logistics and their intarrelationships with engine and frame considerations. Hydrogen production investigations to improve water electrolysis processes, as well as investigation of new methods such as thermochemical processes (C&EN, Sept. 3, page 32), could also involve five- to 10-year programs. Longdistance transmission and bulk storage of hydrogen, including system studies, design limitations, and component development likely would require continuing effort for at least five years. The panel sees public safety and overall system analysis as long-term, lowlevel efforts. However, these efforts are essential to a smooth implementation period and to coordination of the various programs.
Petroleum chemists urged to use TLC PETROLEUM—"It is time for all petroleum chemists to take a more serious look at the quantitative potential of thin-layer chromatography (TLC) for the separation and direct quantitation of heavy hydrocarbon types in air, water, soil, rocks, crude oils, and refined oils as well as their various additives and derivatives." This invitation to participate in a renaissance of TLC was extended by Dr. Theodore T. Martin, of Continental Oil Co., after reviewing recent literature. Without pressing an indictment, Dr. Martin suggests that industry in general and the petroleum industry in particular have been less than open about their experience with TLC. Although he admits that many industrial applications of TLC are proprietary, he emphasizes that TLC is a practical approach to the development of fast, quantitative analytical methods. To some extent Dr. Martin is attempting to revitalize the "crusade" for TLC begun in 1966 by F. C. A. Killer and R. Amos. According to Dr. Martin, Killer and Amos published a formidable package of TLC procedures for separation and identification of petroleum and petroleum products and additives. For unexplained reasons, the 1966 crusade didn't generate much overt enthusiasm, a fact that still puzzles Dr. Martin. One application of TLC from Dr. Martin's new viewpoint is the determination of total diols in fatty alcohols. He says that this procedure is primarily intended for the analysis of C-12 through C-20 alcohols as well as for mixtures of any or all of them. Only slight modifications are required to extend the analytical range to include all alcohols from C-8 through C-24. Sept. 10, 1973 C&EN 19
