Raw materials.-A third area in which primary aluminum producers have been able to reduce or stabilize costs is in raw materials and process supplies. Efforts here fall into several broad categories: 1. Utilization of waste materials-an example is the use of fluosilicic acid waste from the Florida phosphate industry as a raw material for cryolite. 2. Replacement of higher cost with lower cost materials-for example, use of ground sorghum instead of refined cornstarch has reduced operating costs by $1 million annually. 3. Integration of raw materials manufacture with primary processing where attractive purchase arrangement cannot be made. An example is Gramercy where the boilers required for steam production for the alumina plant run extraction turbines which produce power for a caustic-chlorine plant on the site. (Caustic soda is a principal raw material in the manufacture of alumina.) An intermediate stream from the alumina plant is used to make aluminum floride, used in the reduction process. The chlorine from the caustic-chlorine plant offers several future possibilities for chemicals expansion. Hydrogen floride generated from the aluminum flouride plant is used to produce fluorocarbons. Effect of mechanical changes.-Table 3 lists a few examples of mechanical changes which have been made in aluminum fabrication. The tabulation indicates the way in which process improvements and modifications steadily increase production and reduce costs. TABLE 3.-Effect of mechanical changes on operation capacity Description of operation 1. Aluminum wrought ingot is remelted for alloying and casting into sheet rolling ingot in a typical size of 16 by 44 by 112 inches. 2. Sheet rolling ingot is scalped by planing the 44- by 112-inch surfaces prior to hot rolling operation. Mechanical changes Replaced square remelt furnaces having Mechanized scalping operation to achieve 3. Hot rolled coil is further reduced in gage by Replaced 3 to 5 individual cold mill operacold rolling operations. 4. Extrusion billet, which is cylindrical in shape, is loaded into the extrusion press container for extruding into various shapes by pushing the heated aluminum through a díe. 5. Cable stranding from wire... tions on conventional 1 or 2 stand cold Percent capacity increase +18 +8 +17 +11 B. Refractory industry Kaiser Refractories, a division of Kaiser Aluminum & Chemical Corp., is a completely integrated producer of acid and basic group refractories. One common type of refractory is made from periclase (a dense crystalline form of magnesia) and chrome ore. Large tonnages of this refractory are used for lining open hearth and electrical steel-making furnaces, the high temperature zones in cement and lime kilns, glass furnace regenerator systems, copper reverberatory furnaces and converters, and a variety of specialized applications. The principal sources of raw materials for making periclase are natural magnesite (magnesium carbonate), dolomite (calcium magnesium carbonate), sea water, and brine. The process starts with dolomite rock which is quarried, crushed, screened, and calcined in rotary kilns to remove carbon dioxide. Calcined dolomite and pretreated sea water are brought together in huge tanks where a reaction takes place forming magnesium hydroxide. After thickening and filtering, a thick paste of highly pure magnesium hydroxide is fed into rotary kilns along with carefully controlled additives. The resulting product, periclase, is highly refractory and will not appreciably change in size when subjected to further heating. In inland areas, brine from deep wells is utilized for making periclase. At Moss Landing, Calif., Kaiser Refractories operates a plant to produce magnesia and periclase, materials which are used primarily in the manufacture of basic refractories. The plant digests calcined dolomite with softened sea water in a reactor to produce magnesium hydroxide. After thickening and filtering, the hydroxide is burned, together with certain additives, to produce magnesia, usually in the form of periclase. The spent sea water is returned to the sea. Since the plant was built in 1942, a number of major additions and improvements have been made. The time and man-hours required to produce a ton of material has shown a steady decline. The table on the following page shows, at 5-year intervals, the relation between man-hours worked and capacity. Also shown, as a measure of the increase of capacity, are the billions of gallons of sea water processed per year. When the plant was built in 1942, it had one rotary kiln. The capacity was more than doubled when a second and larger rotary kiln was added in 1950. With the increased capacity in 1954, only a few additional man-hours were required. In 1957, another major change was completed with the addition of a third kiln and other major improvements and expansion in the reaction and thickening systems. C. Cement and gypsum The principal production. operations carried out by Kaiser Cement & Gypsum Corp. include the manufacture of portland and special cements, plaster, gypsum wallboard, lath, and sheathing. Cement.-Cement production facilities are located in the States of Washington, California, and Hawaii and have a combined capacity of over 7 billion pounds per year of cement. Limestone, clay, and raw gypsum are the principal raw materials used in cement production. The limestone, a form of calcium carbonate, is quarried, crushed, and ground in a series of grinding operations. After a screening process, the pulverized limestone is pumped in a water suspension to blend tanks, where clay, iron ore, and other elements are added. The agitated "slurry" is fed into revolving kilns which burn the slurry mixture at 2,700° F., producing white-hot clinkers. The clinkers are cooled and pulverized in ball grinding mills. Raw gypsum is added, in varying amounts, prior to the grinding operation to control the setting time of the cement. The initial plant, built in 1939, employed the largest equipment known to the industry at that time. The company's second plant, built at Cushenbury in California's Lucerne Valley in 1957, was outfitted with 1,500-horsepower mills, the largest grinding mills then available. During the 1962-63 expansion the plant was equipped with the West's largest kiln, 16 feet diameter by 520 feet long, and the biggest cement grinding mill in the world, 4,500 horsepower. These giant facilities doubled the plant's capacity with no increase in work force and with striking capital cost benefits. At the same time the larger kilns required 7 percent less fuel per unit of production. Gypsum.-Gypsum plaster and wallboard are made in several locations of Kaiser Gypsum Co., Inc. Raw gypsum ore is the principal raw material for the production of plasters, gypsum wallboard, lath, and sheathing. The ore, a chalklike rock of calcium sulfate dihydrate, is quarried, crushed, and ground to a fine powder. The powder is calcined at a temperature of 250-350° F., which drives out approximately 75 percent of the chemically combined water. The resulting calcium sulfate hemihydrate is reduced to microscopic flakes in a rotating tube mill, partially filled with steel balls. This improves the "stucco's" plasticity, aging properties, and workability when used as plaster. After ball milling, the "stucco" is combined with retarder and other dry ingredients to produce plaster, which is sacked by high-speed machines. For gypsum board products the "stucco" is mixed with paper pulp, foam (to decrease the product density), starch, and water to form a thick slurry. The slurry is discharged onto an unreeling roll of manila paper. Over this goes gray back paper to form a sandwich. The continuous gypsum board sandwich moves on belts and rollers along huge boardmaking machines. The long sandwich is cut into lengths at the end of the board line and dried. Each of the four existing gypsum products plants is designed for efficient, straightline production. The plants have been continually modernized, resulting in increased instrumentation and centralized process control. The new Jacksonville plant incorporates the latest steps toward automation. Specific examples of process improvements in Kaiser Gypsum plants are shown in table 4. TABLE 4.-Specific examples of process improvements, Kaiser Gypsum Co., Inc., 1960-64 Process improvements Effect on process (reductions in cost of 1,000 square feet of wallboard) 1. A method was found for substituting a waste material for a purchased raw material__ 4. A kettle was automated resulting in increased production__ 6. The 1st zone of the dryers was changed from steam heated to direct gas fired, permiting faster drying-----. 5. An improvement was made in the handling of pulp used in the gypsum board core--. 3. A dry weight reduction was made possible by improved additions and product control__ 2. An improvement was made in the method of winding and handling paper rolls.. $0.20 .07 . 12 .03 .20 1.30 .03 7. An improvement in instrumentation to produce more uniform thickness_ D. Steel industry Kaiser Steel Corp. is a fully integrated producer of rolled and fabricated steel; i.e., it mines the ore and coal, and smelts the ore into pig iron and makes and processes steel for sale. The company's steel mill at Fontana, Calif., has been under almost continuous expansion since its initial facilities were built in 1942. The basic raw materials used in steel production-iron ore, coal, and limestone are supplied from the company's western mines and quarries. The ore, which averages 42 percent iron as mined, is upgraded (beneficiated) to 60 percent before shipment. The coal is processed into coke in coke ovens. The beneficiated iron ore, coke, and limestone are fed into the top of the blast furnaces by skip cars. The furnaces smelt the raw materials and reduce them to molten pig iron and slag. At intervals the iron is tapped from the pool of hot metal formed in the hearth of the furnace and is transferred by a "torpedo" car to the steelmaking furnaces. The molten pig iron is then fed into steelmaking furnaces along with steel scrap and other materials, under close quality control, and converted into steel. These steelmaking furnaces are of two types, those using the open hearth method and those using the L-D process, a basic oxygen steelmaking technique. After the steel is tapped, it is poured into molds to form ingots from which, after a brief cooling period, the molds are stripped and the ingots placed in soaking pits until moved to the rolling mills. The first step in rolling takes place in either a stabbing or a blooming mill where the large preheated ingots are rolled into smaller and more easily handled shapes called slabs or blooms. From this primary rolling stage, the steel is distributed among the Fontana plant's nine other rollings mills for finishing to final shape, e.g., sheet, pipe, structural bars, tin plate. High grade iron ore for Fontana's blast furnaces comes from the company's mine at Eagle Mountain, Calif. The ore is mined in huge open pit operations in which overlying rock is stripped to expose the ore. The beneficiation plant upgrades the ore by separating waste materials and low-grade ores from the higher grades to increase the iron content. The production and iron content of the ore shipped from the beneficiation plant has been upgraded by a series of process additions and improvements. In 1953, the annual beneficiated ore production was 1.8 million tons with an iron content of 55 percent. In 1954, heavy media and dry magnetic separation was added for more beneficiation; in 1955, a jig plant; and in the 1961-63 period, a wet magnetic separation process was added and further crushing, blending, and mining improvements were effected. Each of these process improvements has resulted in a higher grade ore for input to the Fontana blast furnaces. In 1964, production increased to 5.2 million tons/year with a 60-percent iron content. At the persent time, a new pelletizing plant is under construction. The pelletizing plant will be equipped with the world's largest pelletizing machine. Though a basic magnetite, the concentrate contains 20 to 50 percent hematite, necessitating a flexible process to yield consistently good pellets from a varying concentrate. Pellet drying, firing, and cooling will all be carried out in one piece of equipment. The potential pig iron production from the four Fontana blast furnaces has increased during the last 7 years from a total of 5,800 net tons/day in 1957 to 6,950 net tons/day in 1964 (a 20-percent increase). Again a key factor in this production increase has been the improvements effected in iron ore beneficiation. This has resulted in a higher iron content in the ore fed to the blast furnaces, less gangue (or mineral contaminants), and better burdening of the Due to the reduced gangue content in the ore, the volume of slag has been correspondingly reduced. Another process improvement, which has resulted in increased potential production, has been the replacement of refractory brick linings with carbon linings. This has increased the effective volume of the blast furnaces. ore. The older method of steelmaking is by the open hearth process. The open hearths are low, rectangular, stationary brick structures with a furnace interior shaped like a shallow dish. Limestone, steel scrap, and molten pig iron are charged through water-cooled doors in the front. The production capabilities of the Fontana furnaces have been considerably enhanced by oxygen enrichment. The first improvement was the use of oxygen in the end wall burners. This increased the average cacapity from 21.9 ingot tons/hour to 28.5 ingot tons/hour, an increase of 30 percent. The most recent innovation has been the use of an oxygen lance through the furnace roof. This has further boosted the average production to 36.1 ingot tons/hour, another increase of 26 percent. TABLE 5.-Specific examples of process improvement, Kaiser Steel Corp., Fontana, Calif.-Period 1957 to 1964 SECTION III. ENERGY CONSUMPTION TRENDS The electrical utility industry in the United States is a clear example of reductions of the cost of a utility service resulting from technological improvements. Part of the reductions in electric power costs have been improvements in the powerplant cycles due to higher temperatures and pressures, made possible by advances in metallurgy and process design. Larger size units have also been important in reducing unit costs and these again have required stronger steels for turbine rotors, new turbine blade designs, and improved boilers. The resulting improvements in efficiency are reflected in the remarkable reduction of pounds of coal used per kilowatt-hour generated and are shown in table 6. The cement industry and steel industry have made similar improvements in energy consumption. The improvements in efficiency in the cement industry are primarily due to increases in kiln size and grinding mill size. The 16-foot diameter by 520-foot-long kilns require 900 cubic feet of natural gas per barrel of cement produced, whereas the 12-foot diameter by 450-foot-long kilns being built in 1957-58 required 1,200 cubic feet of natural gas per barrel produced. The cement industry has also reduced unit electrical energy consumption by increasing the grinding mills from 9.6 feet diameter to about 15 feet diameter. Milling efficiency increases with increasing diameter. A 20-percent energy reduction has resulted from this change. In the steel industry one of the most important cost factors in blast furnace operation is the coke rate (pounds of coke consumed per ton of iron smelted). At Fontana the coke rate has been reduced from 1,490 pounds per ton in 1957 to 1,130 pounds per ton in 1960, a 24-percent reduction within a 7-year period. This has been accomplished through several process improvements: (a) Beneficiation improvements in ore quality. (b) The use of self-fluxing sinter. (c) Natural gas injection. (d) Increasing the temperature of the air supplied to the blast furnace. A portion of these energy gains in the electric utility, cement and steel industries has been accomplished by going to larger sizes. But the increase in efficiency is only a part of the gains in scale up. Gains in capital cost per unit of production may be expected. Section IV describes the effect of scale up. SECTION IV. SOALE UP IN COMPONENT AND PLANT SIZE The reduction in capital costs per unit of production is a commonly expected benefit from increased size. The electric power industry has made great cost reductions by going to larger unit capacity in the fossil fuel installations and is now making greater gains in the nuclear power field. These scale-up, unit-cost factors are shown in table 7. Also shown in this table are the bus-bar energy cost for the nuclear plants: a true measure of overall cost of producing power. 1 Electric World, Oct. 7, 1963, "12th Annual Steam Station Cost Survey." * Electric World, May 1964, “9th Annual Nuclear Power Report." |