Two 75-ton bins Many large mills and a few smaller ones are located on railroads. A railroad connection is desirable and almost necessary for economical large-scale production. If ore from a number of widely scattered mines is to be treated the mill may be built at some central point on a railroad and the ore brought to it. The mill of the Franklin Fluorspar Co. at Marion, Ky., is in the latter class, as crude ore from many mines is brought to it by wagon, truck, and railroad car. At most of the more remote mines the ore is partly cleaned by log washing before it is hauled to Marion. As crude fluorspar ore usually contains 15 to 50 per cent or more waste it is always advisable to concentrate it as near the mine as possible to avoid transporting waste. At some places lack of enough water for milling prevents such treatment. STORAGE AND SHIPMENT PREPARATION FOR SHIPMENT Chute Elevator Chute 5 ft. by 30ft. horizontal drier; drag conveyor: coal fired Screw conveyor Elevator 50-ton bin Chute 33 inch Fuller-Lehigh mill Elevator 15-ton bin Chutes Ground fluorspar is usually elevated to small storage bins, from which it is drawn off and packed in bags or barrels for shipment. There seems to be little uniformity in the fineness of grinding among the various producers. One company makes two sizes, one that will pass a 50-mesh and one an 80-mesh screen. Another mill grinds to about 100 mesh; another (in the West) to only 16 mesh. The product of another company, which makes but one size of ground product, has the following average screen analysis: Product packed by hand in bags or barrels FIGURE 19.-Flow sheet of grind ing mill, Franklin Fluorspar Co., Marion, Ky. One company states that about 75 per cent of its ground spar is packed in canvas or burlap bags holding about 125 pounds each, and the remaining 25 per cent in wooden barrels holding 500 pounds. An operator at Beatty, Nev., proposes to ship ground fluorspar in small paper barrels. STORAGE Gravel-grade fluorspar is stored in several ways. At the two largest mines in the Illinois district finished gravel spar from the mill is run into a large concrete storage bin outside the mill, drained, and partly dried, and transferred to very large concrete storage bins, where the moisture is further reduced by drainage and air drying; the spar is then loaded into railroad cars for shipment. Figure 18 shows storage bins and loading derricks or cranes. At the mill of the Hillside Fluor Spar Mines, near Rosiclare, Ill., the concentrated gravel fluorspar is distributed by a belt conveyor FIGURE 20.-Discharge end of car-loading conveyor, Hillside Fluor Spar Mines, near Rosiclare, Ill. among a series of large concrete bins. Under the row of bins and extending to a railroad siding beyond is a 420-foot belt conveyor with a movable, self-propelled feeder for the conveyor over it, mounted on a carriage and propelled by an electric motor. The feeder may be run up under any bin and set to open the bin gates automatically and feed the belt with spar at an adjustable rate. At the railroad siding the conveyor, inclined upward, discharges through a chute into standard-gauge, hopper-bottom railroad cars. The discharge end of the conveyor is high enough so that the track can be bridged with a conveyor extension and stock piles built up on the far side of one track, should the bins be inadequate for storage. This system of bins and conveyors allows a 50-ton car to be loaded in 35 minutes. Figure 20 shows the discharge end of the conveyor. SHIPMENT RAILROAD SERVICE Only four mines in the southern Illinois district have railroad service, and that only since July, 1919. Before the railroad was built fluorspar was shipped in barges on the Ohio River upstream to Shawneetown for transfer to railroad cars. When the railroad was completed as far as Golconda the Fairview Fluorspar & Lead Co. loaded standard-gauge railroad cars at the mill, hauled them about one-half mile to the river bank, loaded them on a car-ferry barge, towed them to Golconda, and delivered them to the railroad there. Now nearly all fluorspar is shipped by rail, but the spur track down to the river has been used in loading large river barges hold FIGURE 21.-Towboat and barges for fluorspar on Ohio River; Franklin Fluospar Co. landing near Rosiclare, Ill. ing 850 to 1,000 tons with gravel spar for shipment to Pittsburgh. This method of shipment may be used increasingly in the future for shipments to companies operating barges on the river. Figure 21 shows barges and a towboat. RIVER TRANSPORTATION Several mines in the Cave in Rock (Ill.) district must still depend upon river transportation. Ore is hauled to the river and loaded into barges, which are towed to Shawneetown for further shipment in standard-gauge cars. River transportation is uncertain; moreover, the roads are so poor in winter and spring that haulage to the river is usually possible only seven months of the year. ROAD HAULAGE The problem of transportation from mine to railroad is even more acute in the western Kentucky district. With few exceptions the mines are 2 to 18 miles from the nearest railroad siding. No hardsurfaced roads serve the mines; the region has been deeply weathered, and the surface soil is mostly sticky red or brown clay. In wet weather the roads are impassable bogs, and in dry weather repeated passage of heavy loads of fluorspar produces deep ruts and gullies which make hauling, even by wagon, very difficult, slow, and expensive. Figure 22 illustrates hauling conditions at their best. Hauling is practically impossible five to seven months of the year and at intervals during and after rains throughout the rest of the year. FIGURE 22.-Hauling fluorspar over poor roads in Kentucky Practically all hauling is done by two or four horse wagons which hold 1 to 2 tons, usually on contract at a fixed price per ton. Contract prices vary somewhat with the seasons and with the condition of the roads, but average a little less than 25 cents per ton-mile. During the war one company tried hauling by heavy motor trucks. It cost more than wagon haulage, because of repairs and maintenance, but it was more dependable under war conditions. It has been found here, as elsewhere, that a small, irregular output can be moved at relatively low cost; as soon as an attempt is made to maintain a steady, large production haulage costs increase, for systematic, regular haulage must be maintained under all conditions. Several new hard-surfaced roads through parts of this district are in prospect, and it is expected that when they are completed the haulage problems for the mines served by these roads will be solved. MISCELLANEOUS HAULAGE Fluorspar prepared at the mines is hauled to the nearest railroad point, the most important being Marion and Mexico, and unloaded. directly into a car or onto a shipping platform. Stock piles of spar are often allowed to accumulate at the railroad. From these piles the cars are loaded by wheelbarrow. Sometimes the mine product or the log-washed product needs more cleaning before shipment. It is either hauled to one of the concentrating mills at Marion or to the loading dock at Mexico or Crayne, there loaded into railroad cars, shipped to Marion, and unloaded by wheelbarrow to stock piles in the yards of one of the mills. At the Marion mills crude or semifinished fluorspar is stock piled in the mill yards and taken into the mills in wheelbarrows as needed. The finished gravel-grade spar is again taken to stock piles in wheelbarrows and reclaimed in the same way for final shipment. UTILIZATION OF FLUORSPAR The most important uses for fluorspar are in the manufacture of steel by the basic open-hearth process; in the manufacture of opalescent glassware and enamels for metals; in making a substitute for cryolite, used as a bath in producing metallic aluminum by electrolysis; in making hydrofluoric acid and other fluorine chemicals; as a flux in foundry practice, smelting refractory ores, and other metallurgical processes. The distribution of domestic fluorspar shipments in the United States by uses is indicated in the following table. Fluorspar shipped from mines in the United States, 1921-1925, by uses1 1 Figures for 1921-1923 compiled by the U. S. Geological Survey; for 1924-1925 by the Bureau of Mines. |