potential and disposal problems are the same as with spent pickle liquor. Regeneration with hydrochloric acid results in the recovery of a regenerant effluent containing ferrous cliloride and hydrochloric acid. BL- using hydrochloric acid as a regenerant there are available several choices as to further handling. First, the regenerant eluate can be evaporated to recover excess hydrochloric acid which can be recycled as regenerant. The remaining solution is ferrous chloride which can be oxidized t o give ferric chloride. A 6 0 r 0 soiution (saturat,ed) of ferric chloride has been suggested as a pofisible commercjal product (6). By further heating and hydrolysis of the ferrous chloride more hydrochloric acid can be recovered for recycle. The final residue would consist of iron oxide ( I , 2, 4, 6 ) . Khile there may be a limited market for iron oxide as a pigment, it will probably be more desirable to recharge the furnaces with it,. Note that in this process, t,he over-all result is t,he substitut>ionof heat, for chemicals. Sulfuric acid make-up is reduced, and the hydrochloric acid is continuously recycled as a regenerant. A recent publication describes the design and operation of n large plant which processes a solution similar to t h r sprnt, r(1generant to recover iron as iron oxide and chloride as strong 1-1)-drochloric acid ( 1 1 . Spent hydrochloric acid solution that is used t o leach tin ore and that mainly consists of ferrous chloride and other metallic contaminants is neutralized with scrap iron. The solution is concentrated by heating with submerged t?.pe combustion burners. Ferrous chloride is recovered by vacuum
wystallization and then is roast,ed in muffle-type furnaces. The end product,s are iron oxide and 31.5% hydrochloric acid which is re-used. N o cost data on the plant operstion are given. From a technical viewpoint t,he authors conclude that steel inill pickling liquors can be purified using ion exchange resins. In order to make t,he process practical it is essential to recover the chlorides present, in t,he spent regenerant effluent. Complete cost, data for an over-all proeew are not, given since, in order t o be realistic, such a process would have t o be operated on a pilot plant scale for an estend.ed period. ACKN OW LEDGRIENT
The authors are indebted to R. S.Joyce for his assistance in obtaining some of the data and to the National iZluminnte Corp. for permission to publish thi.: paper. The plant pickling liquor \vas kindly supplied bj- the Acme Steel Co. LITERATURE CITED
Chrm. Enu., 61, 114 (1954). Gray, A . G., Steel, p. 130 (April 27, 1953). Hodge, IT-. IF'.. IXD.ESG.CHEM.,31, 1364 (1939). Kunsweiler, J., Deut. Farben-2.. 7, 442 (1953) (5) Ohio River \-alley Sanitation Commission, report prepared 11s Steel Industry Action Committee, 1952. (6) Ruthner, O., Austrian Patent 176,414 (Oct. 2 6 , 1953).
(1) (2) (3) (4)
RECEITED for reviev hlarch 29, 1954.
ACCBPTEDNovember 15, 1954.
Monobed Operation with Problem Water R. V. SI
