Combined grinding and leaching apparatus for ores and wastes and methods of use thereof

Abstract

Disclosed is an apparatus that is an attrition mill for grinding or comminuting ores, mine wastes, and radioactive wastes some of which may comprise metals, which may include uranium and/or cesium and/or mercury and/or thorium and/or rare earth elements. Also disclosed are processes that employ the apparatus for combined grinding and optionally leaching metals from ores and wastes. Some such methods comprise an optional step of grinding and mixing the ore or waste with a solid inorganic base with water addition or with an aqueous inorganic base, follow by a step of grinding and mixing the ore or waste with an aqueous inorganic acid with or without leaching salt addition, to solubilize the metals present in the ore or the waste. The disclosed apparatus and methods, in some embodiments, enable efficient grinding and attrition of ores substrates and mine wastes even without need for grinding media.

1 . An apparatus for grinding or comminuting a metal-containing ore, substrate, mine waste, or radioactive waste, the apparatus comprising:
 a. a container comprising inner walls that define an open end and a closed end for the container, and a lumen for retaining the ore, with two or more elongate ribs projecting inwardly from the walls and extending from the closed end towards the open end of the container;   b. a powered, rotatable spindle extending into and axially aligned with the container, substantially equidistant from side walls of the inner walls of the container;   c. a plurality of grinding arms arranged about and extending from the spindle such that each comprises at least one free end that passes with a clearance of from 0.01 mm to 20 mm from each of the ribs on the inner walls of the container, as the spindle is rotated; and   d. a motor to drive axial rotation of the spindle and attached grinding arms within the container,   
       wherein the apparatus grinds or comminutes the metal-containing ore, substrate or mine waste by grinding and attrition, optionally absent grinding media. 
     
     
         2 . The apparatus of  claim 1 , wherein each grinding arm extends through and extends upon each side of the spindle such that each grinding arm comprises two free ends that each pass with a clearance of from 0.01 mm to 20 mm from each of the ribs on the side walls of the container, as the spindle is rotated. 
     
     
         3 . The apparatus of  claim 1 , wherein successive grinding arms are arranged helically about the spindle such that each successive grinding arm extends at an acute angle from the axis of the spindle relative to its adjacent grinding arm on the spindle, and all grinding arms extend about 90 degrees from an axis of the spindle. 
     
     
         4 . The apparatus of  claim 1 , wherein each grinding arm extends about 90 degrees from each adjacent grinding arm along the spindle, and all grinding arms extend about 90 degrees from an axis of the spindle. 
     
     
         5 . The apparatus of  claim 1 , wherein the grinding arms are at least substantially uniformly elliptical in cross-section, or at least substantially uniformly circular in cross-section, and optionally the grinding arm or arms adjacent the closed end of the container have a substantially square or rectangular cross-section. 
     
     
         6 . The apparatus of  claim 1 , wherein the spindle and attached grinding arms are movable axially relative to the container such that the spindle and grinding arms can be removed from the container, optionally by a telescoping attachment arm. 
     
     
         7 . The apparatus of  claim 1 , wherein the container comprises three or more ribs, at least a portion of which are arranged at least substantially parallel to one another in a radially symmetric manner about the inner walls of the container. 
     
     
         8 . The apparatus of  claim 7 , wherein the container defines a cylindrical lumen and the side inner walls comprise six ribs arranged parallel to one another, at least a portion of which extend a length of the side inner walls from the closed end to the open end of the container, in a radially symmetrical arrangement 60 degrees apart about the axis of the container. 
     
     
         9 . The apparatus of  claim 1 , wherein the inner walls of the container define a cylindrical lumen for the container, defined by a continuous, cylindrical side wall portion extending between the open and closed ends of the container, and a substantially circular floor portion at the closed end of the container, the elongate ribs extending such that they radiate from a centre of said circular portion and continue with a substantially parallel arrangement along said cylindrical side wall portion from the closed end to the open end of the container. 
     
     
         10 . The apparatus of  claim 1 , wherein the plurality of grinding arms comprises from 2 to 20 grinding arms. 
     
     
         11 . The apparatus of  claim 1 , wherein clearance between the free ends of the grinding arms and the ribs is from 0.1-5 mm. 
     
     
         12 . The apparatus of  claim 9 , wherein the grinding arms comprising one or more grinding arms that extend from a free-end of the spindle, which during operation and rotation of the spindle pass adjacent the portion of the elongate ribs that radiate from a centre of the substantially circular floor portion at the closed end of the container, with a clearance of from 0.5-10 mm, preferably less than 5 mm, preferably less than 3 mm. 
     
     
         13 . The apparatus of  claim 1 , wherein the powered, rotatable splindle and/or the grinding arms comprise one or more magnets for collecting magnetic metal components of the ore, substrate or mine waste. 
     
     
         14 . The apparatus of  claim 1 , further comprising air floatation means to add pressured air into the ore, substrate or mine waste being processed, the air floatation means comprising air channels extending within at least some of the grinding arms, each of which exits at least part way along its respective grinding arm, and an air pump to force air through the air channels and out of the grinding arms during rotation of the spindle. 
     
     
         15 . A method for grinding or comminuting a metal-containing ore, substrate, mine-waste, or radioactive waste, comprising the steps of:
 a. adding the metal-containing ore, substrate or mine waste to the container of the apparatus of  claim 1 ;   b. optionally adding a grinding media; and   c. applying power to the motor thereby to rotate the spindle and attached grinding arms, to grind or comminute the metal-containing ore, substrate, mine-waste, or radioactive waste;   
       wherein step a., and optional step b. if present, may be performed in any order. 
     
     
         16 . The method of  claim 15 , further comprising a step of adding to the metal-containing ore, substrate or mine waste, either before, together with or after step a., an aqueous inorganic acid at a concentration of between about 1M and about 9M, at a temperature of less than about 100° C., to solubilize at least a portion of the at least one metal, thereby to produce a mixture of a metal-rich leachate and a metal-poor ore or waste. 
     
     
         17 . The method of  claim 15 , wherein the metal comprises uranium, cesium, mercury, thorium, rare earth elements, or combinations thereof. 
     
     
         18 . The method of  claim 15 , wherein the waste is a cemented radioactive waste or a radioactive mine waste. 
     
     
         19 . The method of  claim 16 , wherein the inorganic acid comprises sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, mixtures thereof, or combinations of inorganic acid and salts thereof. 
     
     
         20 . The method of  claim 16 , further comprising, either before or after the adding of the aqueous inorganic acid, a step of adding an aqueous inorganic base with the addition of water, or with an aqueous organic base at a concentration of from about 1M to about 7.5M, to solubilize at least a portion of the at least one metal providing an aqueous mixture. 
     
     
         21 . The method of  claim 15 , further comprising addition of a leaching salt, wherein the leaching salt comprises a halogen salt such as potassium iodide or a mercury salt such as mercury nitrate, or any combination thereof. 
     
     
         22 . The method of  claim 16 , further comprising a step of: separating the mixture of a metal-rich leachate and a metal-poor ore or waste. 
     
     
         23 . The method of  claim 15 , wherein the method is performed absent any grinding media.