Show sand filling fi ali ng in at ray con BY E D GARDNER of the no 3 mine of the ray consolidated soli dated mining company at ray arizona which extend under the creek and the surface equipment of no 2 mine are filled with waste and further packed with sand to prevent cracking and settling of the capping the ray consolidated under normal conditions dit ions mines about tons of copper ore per day from three foot shafts the ore body is an enormous low grade deposit of the porphyry type it consists of a flat irregular zone fifty to feet thick of impregnated in schist enriched by downward leaching from the upper part in places the belt is leached beached from the surface to depths of feet and the minimum cover at no 3 mine is about feet most of the ore comes from no 1 and no 2 shafts and is mined by a caving system the part of the ore are body worked in no 3 mine is relatively high grade very irregular and as it extends under the creek bed obviously could not be mined by the caving method any settling of the surface would destroy the ore bins at no 2 mine and open cracks through which the flood waters from the creek would fill the mine about sev enty five tons per day are produced from no 3 mine by a square set and fill method A section or panel two sets wide and eight sets long iong is carried up from one level to the next or to the top of the ore and then the space is filled with waste A series of panels in a staga staggered eyed line may be worked at the same time timbers ten inches by ten inches in size are used for the square sets and are doubled with round timbers where required As a rule sufficient waste to fill the is obtained from development work in the three mines but if for any reason the supply is short capping drawn from a finished in no 2 mine is used A raise connects each level of no 3 mine and extends to the surface at the edge e of the railroad track waste brought f from roin no 1 and 2 mines in railroad cars is dumped into this raise and then crammed by hand in one ton cars along the levels to the top of the panel ready to be filled the ore and capping are friable and readily cave in order to keep the capping from cracking the filling must completely fill the openings undue settling of the filling is prevented by flushing sand in at the top of the to fill the interstices in the waste this is done as soon as a panel is finished also sand may be run in while the panel is being filled the worked out are carefully watched and if the filling settles more sand is used at the top to keep the opening tightly packed the sand used which has about the fineness of ordinary building sand is tailing mining 1 engineer Ing ineer of if mines from the companas comp anys concentrator at hayden and is brought to the mine in ore cars on the return trip the dry sand is dumped from the ore cars into a separate raise and crammed by hand in one ton mine cars to the top of the slopes after being emptied from the mine cars the sand is flushed into the slopes by means of a hose water for this purpose is piped from the pump column in the shaft the small amount used readily drains through the filling to the level berow below and finds its way back to the sump for the mine pump the water is clear after leaving the no bulkheads are used at the bottom of the as not enough water is used at any one time to create a hazard if held back the mine is divided into sections by concrete bulkheads for protection in case flood waters from the surface should enter the mine the method of sand filling has proved very successful and the capping has not settled or cracked over any of the no 3 |