Method and System for Solution Mining

Abstract

A relatively warm mineral deposit is solution mined by injecting fluid through a well drilled into the deposit and dissolving the mineral to form a production brine. Warm production brine is cooled at the surface using a heat exchanger as a crystallizer to precipitate the mineral in the exchanger and form a slurry. Crystals of the mineral in the slurry are recovered in a separation plant leaving a relatively cool, dilute or depleted brine, which is conveyed through the heat exchanger for cooling the production brine and then injected into the mineral deposit to dissolve more mineral thereby providing a continuous process. A pipe-in-pipe heat exchanger is preferably used and in a manner so that the heat exchanger also serves as a primary means for conveying the production fluid and/or slurry from the well to the separation plant. This method extracts and recovers the desired mineral(s), recovers much of the heat in the production brine, accelerates the solution mining process since the injection fluid has been warmed, reduces salting in the production string, is relatively inexpensive to install and maintain, and does not require a source of energy for cooling the production brine such as electricity for a refrigeration system.

What is claimed is: 
     
         1 . A crystallizer for use in solution mining a mineral from the earth by circulating a fluid through a deposit of the mineral in the earth for dissolving the mineral; forming crystals of the mineral on the surface of the earth by cooling the circulating fluid in the crystallizer; and recovering the mineral from the circulating fluid with a separation plant, wherein a well extends from the surface of the earth to the mineral deposit, the crystallizer comprising:
 an inner pipe having a first open end and an opposing second open end and a length between the first and second open ends; and   an outer pipe surrounding the inner pipe for essentially the length of the inner pipe,   wherein the inner pipe has an outer surface and the outer pipe has an inner surface,   wherein an annular space is defined between the inner surface of the outer pipe and the outer surface of the inner pipe,   wherein the outer pipe is sealed with the inner pipe proximate to the first open end of the inner pipe and proximate to the second open end of the inner pipe, thereby enclosing the annular space,   wherein the outer pipe has a first port proximate to the first open end of the inner pipe,   wherein the outer pipe has a second port proximate to the second open end of the inner pipe,   wherein the inner pipe has an inside wall surface that defines an inner fluid flow path between the first open end and the second open end of the inner pipe,   wherein an annular fluid flow path is provided from the first port of the outer pipe through the annular space to the second port of the outer pipe,   wherein each of the first open end of the inner pipe and the first port of the outer pipe is in fluid communication with the mineral deposit; and   wherein each of the second open end of the inner pipe and the second port of the outer pipe is in fluid communication with the separation plant.   
     
     
         2 . The crystallizer of  claim 1 , wherein at least one surface of the inner or outer pipe is coated or lined with a substance for minimizing precipitation of the mineral on the coated or lined surface. 
     
     
         3 . The crystallizer of  claim 1 , wherein the first open end of the inner pipe is near the well and the second open end of the inner pipe is near the separation plant so that the length of the inner pipe is approximately the same as the distance between the well and the separation plant. 
     
     
         4 . An apparatus, comprising:
 an inner pipe having an inlet end and an opposing outlet end and a length between the inlet and outlet ends; and   an outer pipe surrounding the inner pipe for essentially the length of the inner pipe,   wherein the inner pipe has an outer surface and the outer pipe has an inner surface,   wherein an annular space is defined between the inner surface of the outer pipe and the outer surface of the inner pipe,   wherein the outer pipe is sealed with the inner pipe proximate to the inlet end of the inner pipe and proximate to the outlet end of the inner pipe, thereby enclosing the annular space,   wherein the outer pipe has an outlet port proximate to the inlet end of the inner pipe,   wherein the outer pipe has an inlet port proximate to the outlet end of the inner pipe,   wherein the inner pipe has an inside wall surface that defines an inner fluid flow path between the inlet end and the outlet end of the inner pipe,   wherein an annular fluid flow path is provided from the inlet port of the outer pipe through the annular space to the outlet port of the outer pipe, and   wherein the length of the inner pipe spans a distance of about a mile.   
     
     
         5 . The apparatus of  claim 4 , wherein at least one surface of the inner or outer pipe is coated or lined with a substance for minimizing precipitation of a mineral on the coated or lined surface. 
     
     
         6 . An apparatus, comprising:
 an inner pipe having an inlet end and an opposing outlet end and a length between the inlet and outlet ends; and   an outer pipe surrounding the inner pipe for essentially the length of the inner pipe,   wherein the inner pipe has an outer surface and the outer pipe has an inner surface,   wherein an annular space is defined between the inner surface of the outer pipe and the outer surface of the inner pipe,   wherein the outer pipe is sealed with the inner pipe proximate to the inlet end of the inner pipe and proximate to the outlet end of the inner pipe, thereby enclosing the annular space,   wherein the outer pipe has an outlet port proximate to the inlet end of the inner pipe,   wherein the outer pipe has an inlet port proximate to the outlet end of the inner pipe,   wherein the inner pipe has an inside wall surface that defines an inner fluid flow path between the inlet end and the outlet end of the inner pipe,   wherein an annular fluid flow path is provided from inlet port of the outer pipe through the annular space to the outlet port of the outer pipe,   wherein the length of the inner pipe can be adapted to extend a long distance such as between a well head for a solution mine and a separation plant for recovering a mineral extracted from the solution mine; and   wherein at least one surface of the inner or outer pipe is coated or lined with a substance for minimizing precipitation of a mineral on the coated or lined surface.   
     
     
         7 . The apparatus of  claim 6 , wherein the length of the inner pipe is about a mile.