| OCR Text |
Show 29 Northern Rhodesia The vanadates, descloizite and vanadinite, have been found associated with zinc-lead mineralization in various localities in Northern Rhodesia. Most of the deposits are small except at Broken Hill, where the Broken Hill mine has produced large quantities of zinc-lead ore which upon milling yields vanadium concentrate as a by-product. The ore is in large lenses with a central core of massive sphalerite (zinc sulfide) and galena (lead sulfide) that produce 30 to 50 per cent combined metal content. Surrounding the massive sulfide is an enveloping oxidized zone containing silica and iron oxide with sufficient zinc silicate, hemimorphite, (HgZngSiOs) and lesser amounts of the zinc and lead carbonates, descloizite and vanadinite to constitute ore. The highest vanadium content is found at the margin of the oxidized ores and in the early history of mining a vanadium content as high as 13 per cent (V205) was obtained by careful hand sorting. Substantial quantities of vanadium have come from Northern Rhodesia, but it is doubtful that much could have been recovered profitably independent of zinc and lead production. In normal times the vanadium concentrate produced in Northern Rhodesia, like the vanadium concentrate from Southwest Africa, is sent to England and Europe for treatment and consumption and not enough has come to the United States to |
