Show OF LOW GRADE COPPER ORES by JOSEPH IRVING leaving those ores which require a roasting treatment with the necessary furnace installation we find that the greater portion of the low grade copper ores which are available partly on dumps and partly in place aggregating millions of tons and which are most ame amenable nabe to a leaching treatment are those having the copper present as carbonates and oxides in a highly gangue and little or no sulphides sulp hides for this class of ore the best treatment is a direct leaching with sulphuric acid as the prime agent it has been proved by careful experiment peri ment conducted on commercial lines that there are many low grade copper propositions ions in these western states which will readily yield up their copper and a fair proportion of their gold and silver to a direct leaching treatment on ores which contain a little copper present as chaleo pyrite or native copper it may be advisable to supplement the leaching by a concentration treatment As a rule iule however a well planned aton method will give on certain ores higher recoveries than a concentration method and at a less cost per pound of copper recovered A method will recover from twenty to twenty five per cent more of the values present than a concentrator will do and take this on a two per cent copper ore it means an extra recovery of at least per ton the product from a plant always commands a good market running as it may from seventy five to ninety per cent copper and being so high in copper there is no heavy freight charge to pay on waste material objection has often been made to the cost of acid and iron in connection with the leaching and recovery of the metals sulphuric acid can be placed at most any point for 30 per ton and at many places for 20 per ton iron can be placed at most points fo 15 per ton the consumption of acid need not exceed two parts of acid to one part of copper and may be considerably less than that while the consumption of iron on can be kept under one and one half pounds to the pound of copper it has been advanced from time to time that gold and silver can not be leached beached out at the same time as the copper by a direct achma method recent practice disproves this however as the writer has produced copper precipitates carrying up to 1 ounce gold per ton ounces silver per ton and 68 per cent copper these were all extracted from the ore sample from utah mall by one treatment and recovered at the same time by precipitation on iron and zinc scrap the table shows some results obtained from western ores on tests varying from one pound to ton lots SOME TESTS ON WESTERN ORES source of gold silver copper copper ore re oz ton oz ton tao ex co nevada heads tails beaver heads utah tails bingham heads utah tails N mex heads tails arizona heads tails nevada heads tails nevada heads tails nevada heads tails tintic gintic heads utah tails product f 1 irom rom above A i A 6 experimental leaching plant various other tests on this tintic gintic ore resulted in a product as previously given the precipitate from the bingham ore gave ounce gold 1416 ounces silver and 87 per cent copper these results obtained on ores from bingham and tintic gintic go to show that it is possible to recover a fair proportion of the gold and silver at the same time as the copper one commendable feature in a direct leaching scheme is its simplicity and cheapness the raw ore going direct birom fa om the crushing plant to the leaching tanks and ahe thence n ce to settlers and the liquor from there to the recovery tanks and flumes blumes of course great care and attention must be devoted to all the mechanical arrangements so that all the work of crushing leaching filtering washing settling and reco recovery veTy can go on steadily without any hitches for a small plant an arrangement like that in the accompanying compa nying illustration might do where the tonnage would be limited to a few hundred tons per day however where thousands of tons for daily treatment were under consider aton large concrete tanks floors and flumes blumes commensurate with the tonnage and backed up by all modern appliances ances for not only treating the ore in quck qu ck time but for getting rid of the waste material would become an absolute necessity and would insure cheap working costs there is no doubt that sulphuric acid with or without salt is the best leaching agent it is quick in action and although somewhat costly is not at all prohibitive with regard to the cost of sulp hurie if some philanthropic smelting smelling sm elting company not altogether disinterested and with an eye to the future would start in and make acid in this western country which would not require to be chemically pure and which might be delivered at half what it costs today to put acid where the low grade copper ores are they would not only give a great impetus to the treatment of low grade copper ores and compounds but other allied chemical industries would start up and the smelting smelling sm elting company would reap an imme immense iise benefit from what had hitherto been not only a dead loss but a source of vexation between the smelter and the a agricultural ri cultural interests te the production of sulphuric would n naturally atu rally tend to eliminate the smoke bogey and that which had been a cause of friction become a good marketable product with regard to the Te recovery covery of the metals electricity will in time no doubt di displace space 1 iron ron but in the meantime iron and zinc are the best mediums they are the cheapest and the simplest and can be had bad in any quantity and no extra plant installation is required the use of iron and zinc as collectors for the metals i e copper gold and silver does not necessarily involve much handling and one great advantage that iron has over electricity today is that copper can be recovered by iron from extremely weak solutions even when containing not more than one tenth of one per cent of copper lime L rne has been tried as a precipitant but did not meet with much favor it has been advanced that the waste liquors from a plant where iron is used as the recovery agent are worthless and cannot be used at again lain experiment has proved that the waste or residual liquors from the tanks wherein the copper has been precipitated by iron can be used over again and to good advantage if proper care is taken this fact aside from the chemical benefit which is derived from the use of these liquors is of great importance in the saving of water which in some parts of the west is a consideration not to oe be despised treatment costs by a direct leaching method under ordinary conditions would run from four cents per pound of copper to six cents per pound of copper taking into consideration that for the same treatment cost a fair amount of silver and gold might be recovered at the same time and without extra expense the treatment would become a small item NOTE in the third line of the second column page 14 of the last issue read 01 per cent copper for ten per cent copper editor |