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Santa Cruz County History - Making a Living
Mineral Survey of Santa Cruz County - Iron
by C. McK. Laizure
Prepared by C. McK. Laizure,
Mining Engineer of the California State Mining Bureau
Triumph Steel Company
This company utilizes the black sand (magnetite) accumulated on the ocean beach, for producing sponge iron, alloy steel and briquetted magnetite. D. M. Crist, president; J. Harris Mackenzie, secretary; L. H. Stowell, plant superintendent. Home office, 112 Market street, San Francisco; plant, Box 252, R. F. D. No. 3, Watsonville, Calif.
The property of the Triumph Steel Company is situated at sea level two miles southeast of Aptos. Trains, however, also stop at the plant, the station being called Cristo.
Research and experimental work on the black sands has been carried on here for several years. Originally a red iron-oxide paint pigment was produced. Later the plant was expanded and the direct production of sponge iron from magnetite begun.
The company owns a site of five acres and 1 3/4 miles of adjacent beach. The process of reducing the magnetite is patented and much of the apparatus in the unit in operation is of original design and manufacture.
The gray-black beach sand is taken by a dragline scraper, operated by an electric hoist and delivered to a bin feeding an elevator. The elevator delivers the sand through a screw feeder to a rotary oil or gas-fired kiln which is used as a drier. After passing through this rotary, the thoroughly dry sand is run to another elevator which discharges into a revolving screen at the top of the plant. This screen, which is about 12-mesh, removes all pieces of shell and coarse gravel which go to the dump.
The fine sand discharges to a hopper feeding the special design magnetic separator. This machine consists of a series of horizontal troughs mounted on a frame standing at an angle of about 80 degrees from the horizontal and reaching from the lower floor to an elevation of about about 40 feet. The sand from the hopper at the top is distributed in a thin film over the top trough and falls by gravity from top to bottom of the separator. In dropping from one trough to another, it passes over magnetic fields of various intensities designed to remove the separate constituents.
Practically all of the magnetite is obtained in the first four troughs. As the sand flows over these, the circuit to the electromagnets is automatically broken three times per second, pulling out and dropping the magnetite into a compartment. As the sand continues to cascade over the remaining sectors the ilmenite and chromite are segregated by regulation of the magnetic fields, each going to separate bins. The quartz garnet and other minerals constitute the tailing which is discharged.
Either pure magnetite, or a combination of magnetite with ilmenite or chromite as desired, is then elevated and fed to a special revolving electric-heated muck-bar tube or kiln, approximately 3 feet in diameter and 35 feet in length. The lining of this tube has nicrome heating elements imbedded, connection being made by two annular copper bands at each end, which revolve with the tube and dip in mercury troughs. Crude oil is sprayed into the feed end of the hot tube as the magnetite passes through it. The oil does not burn but is immediately gassified, the gasses reducing the iron oxide to a metallic condition as sponge iron. The sponge iron is discharged at the lower end into a briquetting press, which delivers the muck-bar billets ready for the market. Gases from the muck-bar tube are drawn off and go to a dephlegmator, which extracts crude oil from them, and delivers an excess of CO gas, for use under the boilers or dryer.
A large amount of direct electric current is used, four days being required to bring the muck-bar tube up to operating temperature after a shut-down. All electricity is generated at the plant which is equipped with a 500-h.p. Babcock and Wilcox boiler and generators having a total of 2000 horsepower. Only a portion of the latter are used in this unit. It is said that no other process will directly produce ferro-titanium.
The plant includes a machine shop, laboratory and housing facilities. Twenty-one men are employed; the full capacity of the present unit being 50 tons of muck-bar per day. An electric furnace for the production of alloy-steel is contemplated.
The development of this direct iron-reduction process has required considerable investment in plant and research. Metallurgically it appears to be workable, but its commercial and economic success has not as yet been definitely proved.
|Bituminous Rock||Gold||Mineral Water|
|Black Sand||Granite||Moulding Sand & Peat|
|Cement||Iron||Petroleum & Potash|
The Mineral Survey of Santa Cruz County was printed in the Santa Cruz Chamber of Commerce Annual Report, 1926. Reproduced by permission of the Santa Cruz Area Chamber of Commerce.
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