Solution mining and a crystallizer for use therein

Abstract

In solution mining, holes are drilled parallel to the ground in the ore body to form a series of zigzag channels. These holes are connected to respective holes from the surface to provide a feed and delivery path and a solvent is circulated through the system so as to dissolve the ore and carry the ore to the surface. The flow of the solvent through the holes forms circular caverns at the intersection of the horizontal hole as well as meanders by eroding the holes so as to gradually extract the ore on each side of the hole. At the surface the ore is extracted in a series of crystallizers each formed by a vessel with an exterior cooling system and an internal wiping system providing shear inside the vessel. The solvent is topped up, reheated and returned to the paths to continue the process.

1 . A method of solution mining comprising:
 identifying an ore body or bodies at a position below ground;   drilling at least one hole from the surface downwardly to an ore body; drilling a hole in a direction generally parallel to the ground to interconnected portions of the ore body to form a series of channels extending through the body;   the holes from the surface being connected to two ends of the interconnected portions to provide a feed path to and a delivery path from the series of channels; and   circulating a solvent through the feed path, the series of channels and the delivery path so as to dissolve the ore and carry the ore to the surface through the delivery channel.   
     
     
         2 . The method according to  claim 1  wherein the holes are drilled vertically to the ore body, then horizontally through the high grade ore zone near the bottom of a selected mine zone in the ore body. 
     
     
         3 . The method according to  claim 1  wherein the holes in the ore body and the flow therethrough are arranged such that caverns develop at the intersection of the holes as the flow is concentrated around the periphery of the cavern. 
     
     
         4 . The method according to  claim 1  wherein the solvent is arranged such that the material exiting through the delivery path is substantially saturated with the dissolved ore. 
     
     
         5 . The method according to  claim 1  wherein the solvent is arranged such that the material exiting through the delivery path is at a temperature at or above the rock temperature at the level of the ore body. 
     
     
         6 . The method according to  claim 1  wherein the material exiting through the delivery path is processed to extract the ore by cooling the material in a crystallizer plant including a series of crystallizers, with the barren brine from the crystallizers being reheated and returned to the mine to dissolve material out of the ore body. 
     
     
         7 . The method according to  claim 6  wherein the processing is carried out without evaporation equipment. 
     
     
         8 . The method according to  claim 6  wherein the crystallizers are arranged for large scale low temperature crystallization. 
     
     
         9 . The method according to  claim 6  wherein each crystallizer comprises a vessel with an exterior cooling system and an internal wiping system providing shear inside the vessel. 
     
     
         10 . The method according to  claim 9  wherein a plurality to wiper blades is provided continually wiping the inner surface of the vessel so that crystal growth is enhanced by direct contact of the solvent with the growing crystal. 
     
     
         11 . The method according to  claim 6  wherein a quantity of water is added to the heated solvent to be returned through the feed path to create the solvent needed to replace the dissolved ore in the mined area. 
     
     
         12 . The method according to  claim 11  wherein the deposition of the salt liberated from the ore in the mined area is returned to the mined area so only minimal amounts of salt ever are brought to surface. 
     
     
         13 . The method according to  claim 1  wherein the solvent temperature is set by adjusting the input brine temperature. 
     
     
         14 . The method according to  claim 1  used on shallow deposits with low rock temperature. 
     
     
         15 . The method according to  claim 1  wherein as needed additional holes from the surface are drilled developing the mine field for returning the ore in solution to the surface. 
     
     
         16 . The method according to  claim 1  wherein the combination of the intersection and meander development creates an undercut of the ore body, with a circular cross section, at the periphery and a thin zone of low flow dissolution over the salt deposit whereby slow dissolution zone extends the cavern vertically over time to dissolve out the entire ore zone. 
     
     
         17 . A method of solution mining comprising:
 identifying an ore body or bodies at a position below ground;   generating a feed path through the ore body or bodies;   circulating a solvent through the feed path, the series of channels and the delivery path so as to carry the ore to the surface through the delivery channel.   wherein the material exiting through the delivery path is cooled to produce product in a simplified crystallizer plant with the barren brine from the crystallisers reheated and returned to the mine to dissolve material out of the ore body;   and wherein a crystallization system is provided for large scale low temperature crystallization applications where high heat exchange is provided through cooling patterns and shear inside the vessel.   
     
     
         18 . The method according to  claim 17  wherein this eliminates the need for expensive evaporation equipment and the high operating cost associated with this equipment. 
     
     
         19 . The method according to  claim 17  wherein the crystallizer has an external recirculation system for developing an upward flow in the bath to maintain the crystals in suspension with a series of blades for wiping the interior surface. 
     
     
         20 . The method according to  claim 17  wherein wiper blades are provided continually wiping the inner surface so that crystal growth is enhanced by direct contact of the solvent with the growing crystals. 
     
     
         21 . The method according to  claim 17  wherein the container of the crystallizer is conical so as to provide an increased flow rate adjacent the bottom.