Show olt oak U t rn theodore P holt who with geo h b dern of this city Is making a success of the mines operating plant at park city has written a detailed account of the new process which has been treating the fillings in the old slopes of the ontario mine says tuesdays evening telegram these fillings carry six to fourteen ounces silver one to two pounds copper 01 tu 05 ounces gold and a small percentage of lead and zinc the treatment consists in mixing the crushed ore with coal dust and salt and then roasting in a new type of furnace by combustion odthe of the contained fuel the roasted ore is leached beached with an acid eld solution to dissolve the silver copper gold and lead and these met als are precipitated together with scrap iron and the product in form sold to the refinery the roasting process Is the feature in this I 1 treatment plan and makes poss possible ible the of ores without any loss of the valuable metals at a veryl very low cost this roasting process had 1 its beginning in connection with thel the rc research search work in the university of utah mines department and I 1 N C christensen Chrls jr was largely responsible tor for the working out of this problem while making experiments with nith the base gold ores of the old mercur mine alter after installing a 3 small test plant at the mercur pro gerties christensen disposed of his big interest to george H dern and a considerable amount of experimenting was conducted at the ontario mine before the present system of roasting was decided upon the leaching process is very simple a solution being made of soluble salts from the roasted ore carrying in ad about four our I 1 acid the acid la Is in part supplied from the condensed roaster fumes the remaining being added from sulphuric acid at such times as tho ore carries a considerable percentage of pyrite no extra acid la Is required in conclusion mr holt says the roasting process Is not limited to but may be advantageously applied to oxidizing gold ores for cyanide treatment and and copper ores tor for subsequent leaching however it Is our opinion that the most favorable field of application Is in roasting 1 in this class of roasting we not only have the benefit ot of cheaper operating cost but in addition have overcome the volatilization loss which in the past has been a serious difficulty we have tested out samples of ore from I 1 thirty eight different mines these I 1 1 ave given us a large variety ol of combinations in many cases the recovery ot of gold old silver and copper has bas been well above 9 90 0 per cent the ideal combination we may sug lest Is a siliceous copper silver ore carrying currying 6 to 10 per cent pyrite and favorably located with respect to a salt supply under such favora favorable conditions ions the entire cost of 0 mill milling in a well designed plant will be less bess than 1 per ton on the basis ot of tons per day when the ore carries gold it is necessary to carry free chlorine in the leaching solutions and adds a few cents to the cost coat of treatment ores high in silica iron and manganese readily A small percentage of lime does I 1 not harm as it is readily neutralized lu in the roast A large percentage however bolever Is detrimental |