Process for Extraction of Recoverable Rare Earth Elements (REE) Using Organic Acids and Chelating Compounds

Abstract

One or more embodiments relates to a process for extracting Rare Earth Elements (REEs) from REE-bearing underclays, claystones, shales, coal-mining waste, and waste coal. In at least one embodiment the process includes contacting the REE-bearing underclays, claystones, shales, coal-mining waste, and waste coal with an Organic Acid Solution (OAS) comprising at least one organic acid and at least one ionic salt at a predetermined ambient temperature and predetermined pH; and separating the REE from the REE-bearing underclays, claystones, shales, coal-mining waste, and waste coal, forming REE+Yttrium (REY) concentrate.

What is claimed is: 
     
         1 . A process for extracting Rare Earth Elements (REEs) from REE-bearing underclays, claystones, shales, coal-mining waste, and waste coal the process comprising:
 contacting the REE-bearing underclays, claystones, shales, coal-mining waste, and waste coal with an Organic Acid Solution (OAS) comprising at least one organic acid and at least one ionic salt at a predetermined ambient temperature and predetermined pH; and   separating the REE from the REE-bearing underclays, claystones, shales, coal-mining waste, and waste coal, forming REE+Yttrium (REY) concentrate.   
     
     
         2 . The process of  claim 1  where separating the REE from the REE-bearing underclays, claystones, shales, coal-mining waste, and waste coal further comprises performing at least one of solid-liquid separating, filtering, drying and calcinating. 
     
     
         3 . The process of  claim 1  wherein the ambient temperature is above the freezing point of the OAS and below 35° C. 
     
     
         4 . The process of  claim 1  wherein the predetermined pH is between about 2 and 6. 
     
     
         5 . The process of  claim 4  wherein the predetermined pH is between about 4 and 5. 
     
     
         6 . The process of  claim 1  wherein the OAS solution comprising the at least one organic acid and the at least one ionic salt follows the formula c (ionic salt)=0.5 mol/L and c (organic acid)=0.1 mol/L where c (ionic salt) is the concentration of ionic salt and c (organic acid) is the concentration of organic acid, the OAS solution having a pH ranging between about 2 and 6. 
     
     
         7 . The process of  claim 1  wherein the process is selected from the group comprising ex-situ heap recovery (ESHR) from clay-rich materials, ex-situ processing plant recovery from clay-rich materials and in-situ recovery (ISR) from clay-rich materials. 
     
     
         8 . A process for extracting Rare Earth Elements (REEs) from REE-bearing materials consisting of underclays, claystones, shales, coal-mining waste, and waste coal, the process comprising:
 contacting the REE-bearing materials with an Organic Acid Solution (OAS) comprising at least one organic acid and at least one ionic salt at a predetermined ambient temperature <35° C. and a predetermined pH between about 2 and 6;   performing at least one of solid-liquid separating, filtering, drying and calcinating; and   separating the REE from the REE-bearing materials, forming REE+Yttrium (REY) concentrate.   
     
     
         9 . The process of  claim 8  where separating the REE from the REE-bearing materials further comprises performing at least one of solid-liquid separating, filtering, drying and calcinating. 
     
     
         10 . The process of  claim 8  wherein the predetermined pH is about 5. 
     
     
         11 . The process of  claim 8  wherein the OAS solution comprising the at least one organic acid and the at least one ionic salt follows the formula c (ionic salt)=0.5 mol/L and c (organic acid)=0.1 mol/L where c (ionic salt) is the concentration of ionic salt and c (organic acid) is the concentration of organic acid. 
     
     
         12 . The process of  claim 8  wherein the specific REE-bearing materials are selected from the group comprising clay rich materials, coal-mining wastes, co-mined materials, undisturbed sedimentary layers, open pits, and underground mines. 
     
     
         13 . The process of  claim 8  wherein the process is selected from the group comprising ex-situ heap recovery (ESHR) from clay-rich materials, ex-situ processing plant recovery from clay-rich materials and in-situ recovery (ISR) from clay-rich materials. 
     
     
         14 . An Organic Acid Solution (OAS) comprising:
 at least one organic acid; and   at least one ionic salt, where the OAS solution follows the formula c (ionic salt)=0.5 mol/L and c (organic acid)=0.1 mol/L where c (ionic salt) is the concentration of ionic salt and c (organic acid) is the concentration of organic acid, the OAS solution having a pH ranging between about 2 and 6.   
     
     
         15 . The OAS solution of  claim 14  having a pH ranging between about 4 and 6. 
     
     
         16 . The OAS solution of  claim 14  having a pH of about 5. 
     
     
         17 . The OAS solution of  claim 14  further comprising at least one chelating compound. 
     
     
         18 . The OAS solution of  claim 14  further comprising at least one surfactant, inorganic acid, colloid, and biocide. 
     
     
         19 . The OAS solution of  claim 14  where the at least one organic solution is selected from the group comprising citric acid, acetic acid, indole-3-acetic acid, gluconic acid and malic acid. 
     
     
         20 . The OAS solution of  claim 14  where the at least one salt is selected from the group comprising (NH 4 ) 2 SO 4 , NaCl and NaH 2 PO 4 . 
     
     
         21 . The OAS solution of  claim 17  where the chelating compound is selected from the group comprising carboxylic acid from acetate, citrate, and formate.