Show STEEL TAKES FLINTS FLINT'S PLACE I IronI I CHICAGO May Hay 19 H Just Just as Iron gave way to steel a deca decade o ae og now flint bows to tho superiority of this competitor and step steps grace grace- gracefully gracefully tully I fully out Importation of o flint pebbles from France and Denmark for tor use lIse us In fromI In- In Industries Industries In Industries I dependent on tine fino grInd grInd- grIndIng Ing of rock roc Jias practically been beAn bc abandoned due to the of steel balls for this purpose ne ac- ac according ac cording to the structural materials research laboratory of o Le LenIn I institute Institute tute tuto here Some Seine sears seara ago aso there was a Il belvy demand for or the tho flit stones otone the tho bulk hulk of which was o oh- oh ob obtained tal ned abroad These flint pebbles according to the announcement were used In Inthe Inthe Inthe the cement ement Industry In tho finer grinding operations where limo limo- stone tone shale shah and clay are reduced to fine Line powder Preliminary crush crush- crushing log ing Is dono done by II a n variety of melh ineth- ineth lods I ode but the wa was waa the Now steel work of o the pebbles I balls aro arc used Long Lone Lon c known as ball or tubo mills mill are half tilled filled with steel balls and wh when n the tho raw materials are arc put In the tho cylinder Is revolved The balls bails climb tho the side of o tho the cylinder and tall fall hick back on the raw materIal and rubbing it to pow pow- powder powder pow powder der Some Somo Som of o the smaller mis- mis ma chines will wilt contain 10 30 or 11 ii ton tons Of ball balls balli w is hile the th largest ones need 34 to 38 ft tons So thorough Is the operation of tho tube t mills that the lock po del produced Is ia finar fin than silk nik Similar machines are aro used In III grinding tho the hard glass 0 clinker to finished cement which I must pass an as equally tine floe test Although some of the California mills still use flint pebbles pebble hie are aro found In that state the major maJor- majority ity ity of the plants use steel hal bl bal from Crom 7 S of an inch to time the inches In diameter Last year ear well welt 45 35 tons of raw materials and 20 OO tons of ot clinker were by the cement Industry In machines of this t pc pe |