Arizona republican., 1915-05-02

ll4tSitSllIlS NOiltHlS
 In recent years the metallurgical
 field of the copper industry has ex-
 banded greatly. the copper ores have
 become lean and diverse in character
 and we are obliged to treat such ores
 on a very large scale.
 l have neither the time nor the
 qualifications to make an inyestiga-
 ton and study in detail of hydro
 metallurgical processes. but I have
 deep interest in the subject and
 have given it in some of it's phases
 careful consideration. l have assisted
 in directing many experiments and
 in reviewing the merits of many pro- cesses. No matter how beautiful the
 process. simplicity and cheapness of
 operating costs are the main fea-
 lures.
 There has been very large de-
 velopment of deposits of lean copper
 ores in the southwest in recent
 years. The vast mass consists of
 sulphide ore. and until recently these
 sulphides alone have. attracted ser
 oius attention. It is well known, how
 ever. that there are large tOnnages
 of oXidized copper ores associated
 with the lean porphvries.
 A few years ago the Calumet and
 Arizona Mining company purchased
 control of the New Cornelia Copper
 company, 1t Ajo Ariz., and system
 atically drilled the property. followed
 by the sinking of some 70 shallow
 shafts for test purposes and open
 ing of two deeper shafts. with con-
 siderable underground development for the purpose of testing and check
 ing the grade of the sulphide ore
 The matrix of the ore is an erup- tive granite. There is no overburden.
 The cEalcocite has been oxidized
 nearly as fast as formed. The zone of transition from oxidized minerals to primary sulphides is narrow. The
 CXide and sulphide ore is remarkably uniform in grade. There are about 40,000.000 tons of ore containing IF per cent copper. divided into about 12,000,000 tons of IF per cent Oxi- dized ore and 24.O00,O ,OOO tons of suI- Phlde ore. with about 1000, 900 tons of mixed oxide and sulphide between If the grade be dropped to an average of less than F. per cent. these ton nages would rapidly increase
 In parallel with this development cXfdized ore in notable tonnages has been found in the Globe mining dis | trict This ore is more scattered, | and, on the whole. is leaner than the [ Ajo, and frequently has a large cap | ping of oVerburden. In the aggregate ! the Inspiration Con. Copper co. alone now has over 15.O00.00O tons of oxi- dized ore running about 13 per cent. and a probable tonnage in addition There are other mines in other dis tricts containing oxidized ore not ably in Utah and Montana. and there Ire also oXidIzed ores at other points l in Arizona and a vast deposit in Chile. The treatment of such ton ! 1ages is of prime importance.
 The Ajo ore has matriX of gran te with large percentage of sec 'ndary quartz replacing feldspar There is little calcium present in soluble form, and the Oxidized ore seems to be best adapted to d leach ng process Tests showed that the Ire crushed with the production of little slime and that the ! copper will dissolve in dilute suIphurlc ( tcid quite freely when the crushed 're contains fragments no larger han 6-mm. cubes. Tests also show sd that little cuprite is present. which is only partly soluble in sul- 1huric acid. There are also other ioluble salts, notably salts of iron md aluminium. It was decided to investigate a teaching process for the 'xidized ore; we decided that we *ould try it in tanks of porcelation The amount of silver in the ore is mall. Salt is apparently expensive. md 1t was decided that. other things 'elng equal, the use of chlorine com bounds as solvents was not desir- lble.
 To me the hydro -metallurgical problem divides iteself naturally into Wo nearly separate divisions-the so- ] ullon Of the copper. and it's recovery rom solution. At the start We em- , 1loyed Stuart Croasdale to undertake | study of the solution of the copper. md we also delegated to him ex- 1erimentation upon the precipitation # copper by iron. Croasdale ably conducted long series of experi- nents Al the same time we were 1 ortunate enough to obtain the ad- , rice of Utley Wedge upon the manu- . acture of sulphuric acid direct from furnace greases.
 MT Croasdale demonstrated that he ore crushed to an S-mm cube pr smaller. would yield over so per ,ent of its copper when treated with dilute solution of sulphuric acid. Also that slime presented no diff aulty if the ore was distributed in he tanks uniformly, and that by liner crushing S5 per cent could be obtained if treated for a sufficient l lme with an acid solution. He dem 1nstrdted not only that the ore was Dermeable uniformly, but that with small tanks the height | vas not matter of great conse- luence. and he was easily able to lse a column 12 it. in height and 'ould probably use one much higher. Later on we found upward percola- ion preferable. 2
 Mir. Wedge showed us that with i are in calcining the sulphide fines I or reverberatory furnaces at the T calumet & Arizona smelter at Doug f as, sulphuric acid of 5 to 6Oo B. q Ould be manufactured with o lo,,, II