PROCESS FOR CO-PRODUCING LITHIUM, ALUMINUM, AND SILICON-OXYGEN (Si-O) MATERIALS

Abstract

The present invention relates generally to a process for co-producing lithium, aluminum, and silicon-oxygen (Si—O) materials, and more particularly, to a process for co-producing lithium, aluminum, and Si—O materials from a hard rock source in the form of a granular concentrate of one or more lithium-containing silicate minerals including spodumene. In particular, there is provided a process for co-producing Li, Al, and Si—O materials from the beta (β) crystallographic form of the Li-containing silicate mineral spodumene, which in its purest state has the composition LiAlSi2O6.

1 . A process for co-producing Li, Al, and Si—O materials from a hard rock source in the form of a granular concentrate of one or more lithium-containing aluminosilicate minerals, including spodumene, comprising:
 providing a hard rock source in the form of a granular concentrate of one or more lithium-containing aluminosilicate minerals, including α-spodumene (Step 1); 
 calcining the granular concentrate at an elevated temperature to obtain a granular concentrate that includes β-spodumene (Step 2); 
 mixing the granular concentrate that includes β-spodumene with an aqueous solution of nitric acid and then agitating or stirring the resulting acidic mixture in a first reactor at a temperature greater than or equal to (≥) about 120° C. and at a pressure greater than or equal to (≥) about 1 atm to effect leaching of Li and Al (Step 3); 
 conveying the acidic mixture to a second reactor to extract N—O—H gas at a temperature greater than or equal to (≥) about 120° C. to form a slurry from which N—O—H gas has been removed (Step 4); 
 conveying the slurry from the second reactor through a cooling unit to a separator where it is divided into two fractions, one fraction rich in leached granular β-spodumene, and the other fraction comprising an aqueous liquid that contains dissolved lithium nitrate (LiNO 3 ) and dissolved aluminum nitrate (Al(NO 3 ) 3 ), wherein the fraction rich in leached granular β-spodumene contains some residual LiNO 3 - and Al(NO 3 ) 3 -containing aqueous liquid formed during Li—Al leaching (Steps 5 and 6); 
 transferring the fraction comprising an aqueous liquid that contains dissolved LiNO 3  and Al(NO 3 ) 3  to a first liquid mixer (Steps 5, 6, and 8); 
 mixing the leached granular β-spodumene-rich fraction with water of sufficient purity, either prior to or after the leached granular β-spodumene-rich fraction enters a mixer-washer, to form a water-slurried leached granular β-spodumene-rich fraction, leading to mixing of the water of sufficient purity with the residual LiNO 3 - and Al(NO 3 ) 3 -containing aqueous liquid formed during Li—Al leaching, to form a wash water containing LiNO 3  and Al(NO 3 ) 3  (Steps 5-7); 
 conveying the water-slurried leached granular β-spodumene-rich fraction to a separator where the solids and liquid are divided into two fractions, one fraction comprising leached granular β-spodumene, and the other fraction comprising the wash water containing LiNO 3  and Al(NO 3 ) 3  (Step 7); 
 transferring the wash water to the first liquid mixer where it coalesces with the previously separated LiNO 3 - and Al(NO 3 ) 3 -containing liquid that enters said first liquid mixer to form a LiNO 3 - and Al(NO 3 ) 3 -containing aqueous liquid (Step 8); 
 optionally, sending the water-washed leached granular solids to an optional reactor where said water-washed leached granular solids are mixed with aqueous/crystalline sodium hydroxide (NaOH) and/or aqueous/crystalline potassium hydroxide (KOH) to produce a (Na and/or K,Li,Al,Si—O)—H 2 O liquid (Step 39); 
 transferring the liquid in the first liquid mixer to a third reactor (Step 9a); and 
 subjecting the LiNO 3 - and Al(NO 3 ) 3 -containing aqueous liquid in the third reactor to treatment that results in formation of a H 2 O-containing aluminous precipitate (“Al(OH) 3 ”) that contains either amorphous Al—O—H solid material or amorphous Al—O—H solid material mixed with quasi-crystalline Al—O—H phases, that treatment comprising one or more of: (i) a heat treatment at a temperature sufficient to decompose the Al(NO 3 ) 3  dissolved in the liquid (Step 9a); (ii) reaction with an aqueous liquid that contains dissolved NH 4 OH (Step 9b); (iii) contact with aqueous (NH 4 ) 2 CO 3  (Step 9c); and (iv) contact with solid (NH 4 ) 2 CO 3  (Step 9c). 
 
     
     
         2 . The process according to  claim 1 , wherein the granular concentrate of one or more lithium-containing aluminosilicate minerals, including α-spodumene, is calcined at a temperature within a range of about 900° C. to about 1200° C. 
     
     
         3 . The process according to  claim 1 , wherein the ambient gas pressure in the second reactor, if greater than about 1 atm, is reduced to about 1 atm to form a slurry from which N—O—H has been removed. 
     
     
         4 . The process according to  claim 1 , wherein the LiNO 3 - and Al(NO 3 ) 3 -containing aqueous liquid in the third reactor is subjected to heat treatment (i) at a temperature of about 180° C. (Step 9a). 
     
     
         5 . A process of co-producing Li, Al, and Si—O materials from a granular concentrate including spodumene in its alpha (α) crystallographic form, comprising:
 providing a granular concentrate including spodumene in its alpha (α) crystallographic form (Step 1); 
 calcining the concentrate at an elevated temperature to convert substantially all of the α-spodumene to the beta (β) crystallographic form (Step 2); mixing the resulting β-spodumene concentrate with an aqueous solution of nitric acid (HNO 3 ) and/or a N—O—H gas plus water (H 2 O), at a temperature ≥about 120° C., and at a pressure between about one atmosphere (1 atm) and about 10 atm, prior to, or after, entry into a first reactor to form an acidic mixture (Step 3); 
 in the first reactor, stirring or agitating the contained acidic mixture for a period of time sufficient to effect leaching of Li and Al from the β-spodumene at ≥about 120° C., and at a pressure ≥about 1 atm (Step 3); 
 conveying the resulting acidic mixture to a second reactor to extract N—O—H gas, wherein, if necessary, ambient gas pressure is reduced to about 1 atm to form a substantially gas-depleted slurry (Steps 3 and 4); 
 conveying the substantially gas-depleted slurry from the second reactor through a cooling unit to a separator, where it is divided into two fractions, one fraction being rich in leached granular β-spodumene and the other fraction comprising an aqueous liquid that contains dissolved lithium nitrate (LiNO 3 ) and dissolved aluminum nitrate (Al(NO 3 ) 3 ) (Steps 4 and 5); 
 transferring the LiNO 3 - and Al(NO 3 ) 3 -containing aqueous liquid to a first liquid mixer (Step 6); 
 mixing the leached granular β-spodumene-rich fraction with water of sufficient purity, either prior to or after the leached granular β-spodumene-rich fraction enters a mixer-washer, to form a water-slurried leached granular β-spodumene-rich fraction, leading to mixing of the water of sufficient purity with the residual LiNO 3 - and Al(NO 3 ) 3 -containing aqueous liquid formed during Li—Al leaching, to form a wash water containing dissolved LiNO 3  and Al(NO 3 ) 3 ; (Steps 5-7); 
 conveying the water-slurried leached granular β-spodumene-rich fraction to a separator where the solids and liquid are divided into two fractions, one fraction comprising leached granular β-spodumene and the other fraction comprising the wash water containing LiNO 3  and Al(NO 3 ) 3  (Step 7); 
 transferring the wash water to the first liquid mixer where it coalesces with the previously separated LiNO 3 - and Al(NO 3 ) 3 -containing liquid that enters said first liquid mixer to form a LiNO 3 - and Al(NO 3 ) 3 -containing aqueous liquid (Steps 7 and 8); 
 optionally, sending the water-washed leached granular solids to a ninth reactor, where they are mixed with (i) aqueous and/or crystalline sodium hydroxide (NaOH) and/or (ii) aqueous and/or crystalline potassium hydroxide (KOH) to produce a (Na and/or K,Li,Al,Si—O)—H 2 O liquid (Step 39); 
 transferring the liquid in the first liquid mixer to a third reactor (Step 8); 
 subjecting the LiNO 3 - and Al(NO 3 ) 3 -containing aqueous liquid in the third reactor to treatment that results in formation of a H 2 O-containing aluminous precipitate (“Al(OH) 3 ”) that contains amorphous Al—O—H solid material or amorphous Al—O—H solid material mixed with quasi-crystalline Al—O—H phases, that treatment comprising one or more of: (i) a heat treatment at a temperature sufficient to decompose the Al(NO 3 ) 3  dissolved in the liquid (Step 9a); (ii) reaction with an aqueous liquid that contains dissolved ammonium hydroxide, NH 4 OH (Step 9b); (iii) contact with aqueous ammonium carbonate, (NH 4 ) 2 CO 3  (Step 9c); and (iv) contact with solid (NH 4 ) 2 CO 3  (Step 9c), with the proviso that when only treatment (i) is used, the process steps further include cooling the slurry flowing out of the third reactor (Step 10); 
 transferring the slurry to a mixer-separator where it is sufficiently stirred and/or agitated and thereafter divided into two fractions, one fraction comprising the aluminous precipitate formed in the third reactor and the other fraction comprising an aqueous liquid that contains dissolved LiNO 3  (Step 11); 
 transferring the fraction comprising an aqueous liquid that contains dissolved LiNO 3 — from the separator to a second liquid mixer (Step 11); 
 mixing the slurry containing Al(OH) 3  with water of sufficient purity and conveying the resulting slurry to a mixer-washer where it is stirred and/or agitated prior to being divided into two fractions, one fraction being rich in Al(OH) 3 , and the other fraction comprising a wash water that contains dissolved LiNO 3  (Steps 11 and 12); 
 conveying the separated fraction comprising the wash water to the second liquid mixer where it coalesces with the previously separated LiNO 3 -containing aqueous liquid transferred to that liquid mixer (Step 12); 
 converting the separated Al(OH) 3  to one or more Al—O—H solids (Step 13 and optional Step 14); 
 transferring the coalesced LiNO 3 -containing aqueous liquid from the second liquid mixer to a fourth reactor (Step 15); 
 combining the coalesced LiNO 3 -containing aqueous liquid in the fourth reactor with NH 3 —CO 2  gas and/or aqueous (NH 4 ) 2 CO 3  and/or solid (NH 4 ) 2 CO 3 , thereby inducing precipitation of solid Li 2 CO 3  with simultaneous formation of aqueous NH 4 NO 3  to form a Li 2 CO 3 —, NH 4 NO 3 —, and (NH 4 ) 2 CO 3 -containing aqueous slurry (Step 16); 
 transferring the Li 2 CO 3 —, NH 4 NO 3 —, and (NH 4 ) 2 CO 3 -containing aqueous slurry from the fourth reactor to a fifth reactor where heating to a temperature of about 100° C., and at a pressure of about 1 atm, results in the decomposition of substantially all remaining dissolved (NH 4 ) 2 CO 3 , as evidenced by production of a NH 3 —CO 2  off gas, to form a Li 2 CO 3 - and NH 4 NO 3 -containing slurry (Steps 16 and 17); 
 cooling the Li 2 CO 3 - and NH 4 NO 3 -containing slurry flowing out of the fifth reactor, and then transferring it to a mixer-separator where it is stirred and/or agitated, and thereafter divided into two fractions, one fraction comprising the solid Li 2 CO 3  formed in the fourth reactor and the other fraction comprising a NH 4 NO 3 -containing aqueous liquid (Steps 18 and 19); 
 transferring the NH 4 NO 3 -containing aqueous liquid to a third liquid mixer, and mixing the fraction comprising the solid Li 2 CO 3  with water of sufficient purity prior to sending it to a mixer-washer where it is stirred and/or agitated, the result being formation and separation, in a separator connected to the mixer-washer, of a wash water that contains dissolved NH 4 NO 3  (Steps 19 and 20); 
 transferring the NH 4 NO 3 -containing wash water to the third liquid mixer where it coalesces with the previously-separated NH 4 NO 3 -containing aqueous liquid that enters that liquid mixer (Step 20); 
 optionally, conveying the moist Li 2 CO 3  from the separator to a dryer, and optionally thereafter transferring the dried Li 2 CO 3  to a chemical conversion system, or optionally transferring the moist Li 2 CO 3  from the separator directly to the chemical conversion system where the chemical conversion system is used to convert or react Li 2 CO 3  to produce aqueous LiOH and/or solid LiOH·xH 2 O (x=1, 2, 3, or 6) (Steps 20-22); 
 upon its exit from the third liquid mixer, optionally heating the NH 4 NO 3 -containing aqueous liquid to a temperature of about 120° C. as it flows toward an additional mixer where it is combined with an excess amount of solid magnesium oxide (MgO), the MgO optionally being preheated prior to its mixing with the NH 4 NO 3 -containing aqueous liquid, to form a multiphase material (Steps 23 and 24); 
 conveying the multiphase material from the additional mixer to a sixth reactor where its temperature is maintained at about 120° C., which results in the formation of an aqueous slurry of magnesium nitrate (Mg(NO 3 ) 2 ) and magnesium hydroxide (Mg(OH) 2 ), and NH 3  gas (Steps 24 and 25); 
 conveying the NH 3  to a gas mixer where it is combined with both provided CO 2  and the NH 3 —CO 2  gas produced in the fifth reactor (Steps 25 and 26); 
 conveying the mixed NH 3 —CO 2  gas through a cooling unit, and thereafter recycling it back to precipitate additional Li 2 CO 3  (Step 16), or optionally sending it to a seventh reactor where it is mixed with H 2 O to form aqueous (NH 4 ) 2 CO 3 , the resulting (NH 4 ) 2 CO 3 -containing aqueous liquid then being recycled back to precipitate additional Li 2 CO 3  (Steps 26 and 27); 
 transferring the aqueous slurry co-produced in the sixth reactor—it comprising Mg(NO 3 ) 2 , Mg(OH) 2 , and H 2 O—to a mixer where it is stirred and/or agitated and thereafter separated into two fractions, one fraction containing Mg(OH) 2 -rich solids and the other fraction being an aqueous liquid that contains dissolved Mg(NO 3 ) 2  (Steps 25 and 28); 
 conveying the Mg(NO 3 ) 2 -containing aqueous liquid to a fourth liquid mixer (Step 28); 
 mixing the Mg(OH) 2 -rich solids with water, and then sending the resulting slurry to a mixer-washer where it is stirred and/or agitated, the result being formation of a wash water that contains dissolved Mg(NO 3 ) 2  (Steps 28 and 29); 
 transferring the Mg(OH) 2 - and Mg(NO 3 ) 2 -containing aqueous slurry to a separator where it is divided into two fractions, one fraction comprising moist Mg(OH) 2  plus any residual MgO, and the other fraction being the Mg(NO 3 ) 2 -containing wash water formed in the mixer-washer (Step 29); 
 transferring the Mg(NO 3 ) 2 -containing wash water to the fourth liquid mixer where it coalesces with the previously-separated Mg(NO 3 ) 2 -containing aqueous liquid which enters that liquid mixer (Step 29); 
 transferring a portion of the moist Mg(OH) 2 ±MgO to a first furnace where it is heated to a maximum temperature of about 600° C., the result being production of MgO and water vapor, the MgO being recycled back to Step 24 (Steps 29 and 33); 
 transferring the Mg(NO 3 ) 2 -containing aqueous liquid from the fourth liquid mixer to an evaporator where it is heated to a temperature of about 150° C., which initiates production of molten Mg(NO 3 ) 2 ·xH 2 O (x≤6), water vapor, and any generated N—O—H gas (Steps 30 and 31); 
 after exiting the evaporator, conveying the H 2 O-depleted Mg(NO 3 ) 2 ·xH 2 O liquid to a mixer where it is blended with a portion of the moist Mg(OH) 2 ±MgO produced previously (Step 29) (Steps 31 and 32); 
 transferring the Mg(NO 3 ) 2 ·xH 2 O—Mg(OH) 2 ±MgO slurry from the mixer to a second furnace where it is heated up to a maximum temperature of about 600° C., the purpose being to form MgO plus solid impurities, along with a NO 2 - and O 2 -containing N—O—H gas (Steps 32 and 34); 
 conveying the MgO+solid impurities to a mixer-washer where the solids are slurried with a liquid in which MgO is substantially insoluble, but also in which the solid impurities are substantially soluble (Steps 34 and 35); 
 stirring or agitating the MgO-containing slurry prior to sending it to a separator where it is divided into two fractions, one fraction comprising MgO, which is recycled back to Step 24, and the other fraction being the liquid that is enriched in impurities (Step 35); 
 optionally treating the liquid in a way that divides it into two fractions, one fraction being a purified liquid and the other fraction comprising the impurities present in the liquid fraction formed in the separator (Step 36); 
 optionally recycling the purified liquid back to the earlier step wherein MgO+solid impurities was slurried with the originally provided liquid (Step 36); 
 conveying (i) the N—O—H gas removed from the second and third reactors, and also (ii) the N—O—H gas produced in the evaporator (if any), and also (iii) the NO 2 -, O 2 - and H 2 O-containing N—O—H gas formed in the second furnace, to a gas mixer where the individual streams of gas intermingle (Step 37); 
 conveying the N—O—H gas from the gas mixer back to the first reactor, and/or to an eighth reactor where it is mixed into H 2 O to produce aqueous HNO 3  that is subsequently sent back to the first reactor (Step 38).