DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 8 December 2025 has been entered.
Response to Amendment
The Amendment filed 8 December 2025 has been entered. Claim 12 is amended; claim 16 is cancelled. Accordingly, claims 12-15 and 17-20 remain pending in the application.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claim 12 is rejected under 35 U.S.C. 103 as being unpatentable over Fang (CN 112758971) in view of Worsley (US 2015/0086452), as evidenced by Gulbrandsen ("Chemical composition of phosphorites of the Phosphoria Formation"), and further in view of Wrubel (US 2015/0321924) and Hunwick (US 2021/0387860).
Regarding Claim 12, Fang discloses a method for separating calcium and magnesium from a calcium-magnesium leaching solution of chemical ore dressing byproduct (separating calcium and magnesium from a calcium-magnesium leaching solution of chemical ore dressing byproduct meets the limitation of reducing alkaline earth metals in solids, as calcium and magnesium are alkaline earth metals, and ore meets the limitation of solids; pg. 8, paragraph 3), wherein the calcium-containing magnesium leaching liquid can be obtained by taking low-grade phosphorite as raw material (low-grade phosphorite is the ore of the ore dressing byproduct, and meets the limitation of solids), crushing, calcining, leaching, and filtering; the liquid discharged from the filter press is the calcium-containing magnesium leaching liquid (leaching phosphorite meets the limitation of acid-leaching the solids; pg. 4, par. 12-pg. 5, par. 1). Fang further discloses a decalcification reaction of the leaching liquid with crude nitrate calcium liquid and potassium sulphate to produce a slurry, and solid-liquid separation of the slurry to obtain a decalcified liquid and calcium sulphate (decalcified liquid meets the limitation of an effluent slurry; claim 1); neutralizing the decalcified liquid to form a neutralized liquid (neutralizing the decalcified liquid meets the limitation of neutralizing the effluent slurry to form a neutralized filtrate; claim 1); concentrating the neutralized liquid by evaporation in a forced circulation type evaporator (pg. 8, paragraph 1); wherein concentrating the neutralized liquid takes place prior to crystallization (pg. 3, par. 6); crystallizing potassium nitrate from the neutralized liquid in a crystallization step (potassium nitrate appears to meet the limitation of impurities; claim 1); and carrying out a magnesium removing reaction to obtain magnesium hydroxide (a magnesium removing reaction to obtain magnesium hydroxide meets the limitation of precipitating remaining impurities; claim 1).
Fang is silent to concentrating the neutralized filtrate by Mechanical Vapor Recompression heating falling film evaporators.
Fang, however, teaches concentrating the neutralized liquid by evaporation in a forced circulation type evaporator (pg. 8, paragraph 1).
Worsley discloses concentrating via evaporation (claim 1) by falling film MVR evaporators (falling film MVR evaporator meets the limitation of Mechanical Vapor Recompression heated falling film evaporator; claim 19, [0033]), which are evaporators known to have high rate of heat transfer and high energy efficiency (claim 19).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Fang to incorporate the teachings of Worsley to concentrate the neutralized filtrate by Mechanical Vapor Recompression heated falling film evaporators in order to evaporate with a high rate of heat transfer and high energy efficiency, as recognized by Worsley (claim 19).
Fang is further silent to holding a lithium concentration in the neutralized filtrate below a lithium target concentration to avoid crystallizing a lithium-potassium double salt when the neutralized filtrate leaves the Mechanical Vapor Recompression heated falling film evaporator.
Fang, however, discloses concentrating a neutralized liquid by evaporation in a forced circulation type evaporator (pg. 8, paragraph 1), and the solids of Fang is low-grade phosphorite (pg. 4, par. 12-pg. 5, par. 1).
Gulbrandsen discloses the chemical composition of phosphorite includes SiO2, Al2O3, Fe2O3, MgO, CaO, Na2O, K2O, H2O, H2O−, TiO2, P2O5, CO2, SO3, F, organic matter, oil, and uranium (Abstract), such that phosphorite does not contain lithium.
Fang is silent to the presence of lithium in the neutralized liquid, and the phosphorite solids of Fang do not contain lithium, such that the neutralized filtrate of Fang does not contain lithium. A lithium concentration of zero necessarily meets the limitation wherein a lithium concentration in the neutralized filtrate is held below a lithium target concentration to avoid crystallizing a lithium-potassium double salt when the neutralized filtrate leaves the Mechanical Vapor Recompression heated falling film evaporator.
Fang is further silent to crystallizing impurities from the neutralized filtrate in a first crystallization step in a forced circulation crystallizing step; crystallizing impurities from the neutralized filtrate in a second crystallization step in a first draft tube crystallizing step; crystallizing impurities from the neutralized filtrate in a third crystallization step in a second draft tube crystallizing step.
Fang, however, teaches crystallizing potassium nitrate from the neutralized liquid in a crystallization step (potassium nitrate appears to meet the limitation of impurities; claim 1).
Wrubel discloses crystallizing potassium nitrate (the impurity crystallized in Fang) [0095], wherein the crystallizer is a forced circulation crystallizer, draft tube baffle crystallizer, or any combination thereof [0064].
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Fang to incorporate the teachings of Wrubel to crystallize impurities from the neutralized filtrate in a first crystallization step in a forced circulation crystallizing step; crystallize impurities from the neutralized filtrate in a second crystallization step in a first draft tube crystallizing step; crystallize impurities from the neutralized filtrate in a third crystallization step in a second draft tube crystallizing step, because crystallizing in multiple steps is a process parameter well-known in the art of crystallization, as taught by Wrubel, in order to further improve the removal of impurities (i.e. potassium nitrate), absent a showing of unexpected results through routine experimentation (MPEP 2144.04 IV B).
Fang is further silent to precipitating remaining impurities via addition of a caustic material.
Fang, however, teaches carrying out a magnesium removing reaction to obtain magnesium hydroxide (a magnesium removing reaction to obtain magnesium hydroxide meets the limitation of precipitating remaining impurities; claim 1).
Hunwick discloses milk of lime (milk of lime meets the limitation of a caustic material) may be added to a blend of potassium, magnesium and lithium with chloride to precipitate the magnesium as insoluble magnesium hydroxide (magnesium hydroxide meets the limitation of an impurity) in order to remove magnesium, which can be a problem when present in high concentrations because both its sulphate and chloride are quite soluble in aqueous solutions [0109].
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Fang to incorporate the teachings of Hunwick to precipitate remaining impurities via addition of a caustic material in order to remove magnesium, which can be a problem when present in high concentrations because both its sulphate and chloride are quite soluble in aqueous solutions, as recognized by Hunwick [0109].
Claims 13 and 14 are rejected under 35 U.S.C. 103 as being unpatentable over Fang (CN 112758971) in view of Worsley (US 2015/0086452) and Wrubel (US 2015/0321924) and Hunwick (US 2021/0387860) and Gu (CN 101724748).
Regarding Claim 13, Fang, Worsely, Wrubel, and Hunwick teaches the elements as described above with regards to claim 12.
Fang discloses a calcium-magnesium leaching solution of chemical ore dressing byproduct (pg. 8, paragraph 3).
Fang is silent to using sulfuric acid for acid leaching of the solids, and wherein a temperature of the acid leaching of the solids is between 75°C and 90°C.
Gu discloses acid leaching magnesium-containing ore using sulfuric acid (Abstract), wherein a temperature of the acid leaching of the ore is between 75°C and 80°C [0048].
Regarding the temperature of acid leaching in claim 13, between 75°C and 80°C taught by Gu meets the limitation of between 75°C and 90°C.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Fang to incorporate the teachings of Gu wherein acid leaching of the solids uses sulfuric acid, and wherein a temperature of the acid leaching of the solids is between 75°C and 90°C, because using sulfuric acid and temperatures between 75°C and 90°C for acid leaching are process parameters well-known in the art of acid-leaching magnesium-containing ore, as taught by Gu.
Regarding Claim 14, Fang discloses carrying out a magnesium removing reaction to obtain magnesium hydroxide (a magnesium removing reaction to obtain magnesium hydroxide meets the limitation wherein the precipitated impurity is magnesium hydroxide; claim 1).
Fang is silent to precipitating magnesium hydroxide with a caustic material, wherein the caustic material is milk-of-lime.
Hunwick discloses milk of lime may be added to a blend of potassium, magnesium and lithium with chloride to precipitate the magnesium as insoluble magnesium hydroxide in order to remove magnesium, which can be a problem when present in high concentrations because both its sulphate and chloride are quite soluble in aqueous solutions [0109].
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Fang to incorporate the teachings of Hunwick wherein the caustic material is milk-of-lime, and wherein the precipitated impurity is magnesium hydroxide in order to remove magnesium, which can be a problem when present in high concentrations because both its sulphate and chloride are quite soluble in aqueous solutions, as recognized by Hunwick [0109].
Claim 15 is rejected under 35 U.S.C. 103 as being unpatentable over Fang (CN 112758971) in view of Worsley (US 2015/0086452) and Wrubel (US 2015/0321924) and Hunwick (US 2021/0387860) and Gu (CN 101724748) and Rastas (US 6,274,104).
Regarding Claim 15, Fang, Worsley, Wrubel, Hunwick, and Gu teach the elements as described above with regards to claim 14.
Fang discloses carrying out a magnesium removing reaction to obtain magnesium hydroxide (claim 1).
Fang is silent to recycling the magnesium hydroxide to neutralize the effluent slurry.
Rastas discloses precipitating magnesium hydroxide using calcium hydroxide (milk-of-lime is a calcium hydroxide solution and therefore precipitating magnesium hydroxide using calcium hydroxide meets the limitation of precipitating via the addition of milk-of-lime; Col. 8, lines 36-38), wherein the magnesium hydroxide can be reused as a neutralizing agent (Col. 1, line 67-Col. 2, line 1).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Fang to incorporate the teachings of Rastas wherein the magnesium hydroxide is recycled to neutralize the effluent slurry as magnesium hydroxide is a known neutralizing agent, as recognized by Rastas, and recycling is a well-known beneficial process which conserves resources.
Claim 17 is rejected under 35 U.S.C. 103 as being unpatentable over Fang (CN 112758971) in view of Worsley (US 2015/0086452) and Wrubel (US 2015/0321924) and Hunwick (US 2021/0387860) and Gu (CN 101724748) and Blei (US 2022/0356152).
Regarding Claim 17, Fang, Worsley, Wrubel, and Hunwick teach the elements as described above with regards to claim 12.
Fang is silent to using Mechanical Vapor Recompression heated falling film evaporators to evaporate the neutralized filtrate at approximately 105°C.
Fang, however, discloses concentrating the neutralized liquid by evaporation at 100°C to 135°C (claim 6).
Regarding the evaporation temperature in claim 17, it appears that 100°C to 135°C taught by Fang overlaps the claimed value of 105°C such that the range taught by Fang obviates the claimed value. See MPEP 2144.05 (I).
Worsley discloses concentrating via evaporation (claim 1) by falling film MVR evaporators (falling film MVR evaporator meets the limitation of Mechanical Vapor Recompression heated falling film evaporator; claim 19, [0033]), which are evaporators known to have high rate of heat transfer and high energy efficiency (claim 19).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Fang to incorporate the teachings of Worsley wherein the Mechanical Vapor Recompression heated falling film evaporators evaporate the neutralized filtrate at approximately 105°C in order to evaporate with a high rate of heat transfer and high energy efficiency, as recognized by Worsley (claim 19).
Fang is further silent to the first crystallization step occurring at approximately 65°C; the second crystallization step occurring at approximately 40°C; and the third crystallization step occurring at approximately 10°C.
Fang, however, teaches crystallizing potassium nitrate at room temperature (pg. 6, paragraph 9), which is between the claimed values of 40°C for the second crystallization step and 10°C for the third crystallization step.
Blei discloses crystallization in three steps with decreasing temperatures from step to step, with the first step occurring at 70°C to 110°C, the second step occurring at 20°C to 70°C, and the third step occurring at -10°C to 25°C [0048].
Regarding the first crystallization step temperature in claim 17, it appears that 70°C to 110°C taught by Blei is close to the claimed value of 65°C such that the range taught by Blei obviates the claimed range. See MPEP 2144.05 (I).
Regarding the second crystallization step temperature in claim 17, it appears that 20°C to 70°C taught by Blei overlaps the claimed value of 40°C such that the range taught by Blei obviates the claimed range. See MPEP 2144.05 (I).
Regarding the third crystallization step temperature in claim 17, it appears that -10°C to 25°C taught by Blei overlaps the claimed value of 10°C such that the range taught by Blei obviates the claimed range. See MPEP 2144.05 (I).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Fang to incorporate the teachings of Blei wherein the first crystallization step occurs at approximately 65°C; the second crystallization step occurs at approximately 40°C; and the third crystallization step occurs at approximately 10°C, because decreasing temperatures from step to step when crystallizing in multiple steps is a process parameter well-known in the art of crystallization, as taught by Blei, in order to further improve the removal of impurities, absent a showing of unexpected results through routine experimentation (MPEP 2144.04 IV B).
Claim 18 is rejected under 35 U.S.C. 103 as being unpatentable over Fang (CN 112758971) in view of Worsley (US 2015/0086452) and Wrubel (US 2015/0321924) and Hunwick (US 2021/0387860) and Gu (CN 101724748) and Blei (US 2022/0356152) and Phinney (US 2011/0123420).
Regarding Claim 18, Fang, Worsley, Wrubel, Hunwick, Gu, and Blei teach the elements as described above with regards to claim 17.
Fang is silent to cooling by water from a cooling tower in the crystallization step.
Phinney discloses a crystallizer is cooled by water from a cooling tower [0049].
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Fang to incorporate the teachings of Phinney wherein the second crystallization step is cooled by water from a cooling tower, because using water for cooling in crystallization is a process parameter well-known in the art of crystallization, as taught by Phinney.
Claims 19 and 20 are rejected under 35 U.S.C. 103 as being unpatentable over Fang (CN 112758971) in view of Worsley (US 2015/0086452) and Wrubel (US 2015/0321924) and Hunwick (US 2021/0387860) and Gu (CN 101724748) and Blei (US 2022/0356152) and Phinney (US 2011/0123420) and Morrison (US 4,409,253).
Regarding Claim 19, Fang, Worsley, Wrubel, Hunwick, Gu, Blei, and Phinney teach the elements as described above with regards to claim 18.
Fang is silent to cooling by a glycol-water mixture in the crystallization step.
Morrison discloses a crystallization step is cooled with an ethylene glycol-water mixture (Col. 11, lines 59-61).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Fang to incorporate the teachings of Morrison wherein the third crystallization step is cooled with a glycol-water mixture, because using a glycol-water mixture for cooling in crystallization is a process parameter well-known in the art of crystallization, as taught by Morrison.
Regarding Claim 20, Fang is silent to cooling by a glycol-water mixture in the crystallization step, wherein the glycol mixture comprises ethylene glycol.
Morrison discloses a crystallization step is cooled with an ethylene glycol-water mixture (Col. 11, lines 59-61).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Fang to incorporate the teachings of Morrison wherein the glycol-water mixture comprises ethylene glycol, because using an ethylene glycol-water mixture for cooling in crystallization is a process parameter well-known in the art of crystallization, as taught by Morrison.
Claim 12 is rejected under 35 U.S.C. 103 as being unpatentable over Fang (CN 112758971) in view of Worsley (US 2015/0086452) and Nishikawa (JP 2022164547) and Wrubel (US 2015/0321924) and Hunwick (US 2021/0387860).
An alternative rejection of claim 12 is provided in case the neutralized filtrate contains lithium.
Alternatively, regarding Claim 12, Fang discloses a method for separating calcium and magnesium from a calcium-magnesium leaching solution of chemical ore dressing byproduct (separating calcium and magnesium from a calcium-magnesium leaching solution of chemical ore dressing byproduct meets the limitation of reducing alkaline earth metals in solids, as calcium and magnesium are alkaline earth metals, and ore meets the limitation of solids; pg. 8, paragraph 3), wherein the calcium-containing magnesium leaching liquid can be obtained by taking low-grade phosphorite as raw material (low-grade phosphorite is the ore of the ore dressing byproduct, and meets the limitation of solids), crushing, calcining, leaching, and filtering; the liquid discharged from the filter press is the calcium-containing magnesium leaching liquid (leaching phosphorite meets the limitation of acid-leaching the solids; pg. 4, par. 12-pg. 5, par. 1). Fang further discloses a decalcification reaction of the leaching liquid with crude nitrate calcium liquid and potassium sulphate to produce a slurry, and solid-liquid separation of the slurry to obtain a decalcified liquid and calcium sulphate (decalcified liquid meets the limitation of an effluent slurry; claim 1); neutralizing the decalcified liquid to form a neutralized liquid (neutralizing the decalcified liquid meets the limitation of neutralizing the effluent slurry to form a neutralized filtrate; claim 1); concentrating the neutralized liquid by evaporation in a forced circulation type evaporator (pg. 8, paragraph 1); wherein concentrating the neutralized liquid takes place prior to crystallization (pg. 3, par. 6); crystallizing potassium nitrate from the neutralized liquid in a crystallization step (potassium nitrate appears to meet the limitation of impurities; claim 1); and carrying out a magnesium removing reaction to obtain magnesium hydroxide (a magnesium removing reaction to obtain magnesium hydroxide meets the limitation of precipitating remaining impurities; claim 1).
Fang is silent to concentrating the neutralized filtrate by Mechanical Vapor Recompression heating falling film evaporators.
Fang, however, teaches concentrating the neutralized liquid by evaporation in a forced circulation type evaporator (pg. 8, paragraph 1).
Worsley discloses concentrating via evaporation (claim 1) by falling film MVR evaporators (falling film MVR evaporator meets the limitation of Mechanical Vapor Recompression heated falling film evaporator; claim 19, [0033]), which are evaporators known to have high rate of heat transfer and high energy efficiency (claim 19).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Fang to incorporate the teachings of Worsley to concentrate the neutralized filtrate by Mechanical Vapor Recompression heated falling film evaporators in order to evaporate with a high rate of heat transfer and high energy efficiency, as recognized by Worsley (claim 19).
Fang is further silent to holding a lithium concentration in the neutralized filtrate below a lithium target concentration to avoid crystallizing a lithium-potassium double salt when the neutralized filtrate leaves the Mechanical Vapor Recompression heated falling film evaporator.
Fang, however, discloses concentrating a neutralized liquid by evaporation in a forced circulation type evaporator (pg. 8, paragraph 1).
Nishikawa discloses a method for recovering lithium from a lithium-ion secondary battery (lithium-ion secondary battery meets the limitation of solids) comprising: a lithium leaching step, a membrane separation step, and a calcium removal step (calcium removal meets the limitation of reducing alkaline earth metals; [0011]). Nishikawa further discloses by setting the lithium concentration of the first lithium concentrated solution to less than 4,000 mg/L, it is possible to prevent crystallization (preventing crystallization of lithium necessarily prevents the crystallization of a lithium-potassium double salt) and clogging of lithium carbonate on the membrane surface during membrane separation, and it becomes possible to perform continuous, stable membrane separation over a long period of time [0038] and allows for later recovery of a high-purity lithium salt [0014].
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Fang to incorporate the teachings of Nishikawa to hold a lithium concentration in the neutralized filtrate below a lithium target concentration to avoid crystallizing a lithium-potassium double salt when the neutralized filtrate leaves the Mechanical Vapor Recompression heated falling film evaporator in order to recover a high-purity lithium salt after removing alkaline earth metal impurities, as recognized by Nishikawa [0014].
Fang is further silent to crystallizing impurities from the neutralized filtrate in a first crystallization step in a forced circulation crystallizing step; crystallizing impurities from the neutralized filtrate in a second crystallization step in a first draft tube crystallizing step; crystallizing impurities from the neutralized filtrate in a third crystallization step in a second draft tube crystallizing step.
Fang, however, teaches crystallizing potassium nitrate from the neutralized liquid in a crystallization step (potassium nitrate appears to meet the limitation of impurities; claim 1).
Wrubel discloses crystallizing potassium nitrate (the impurity crystallized in Fang) [0095], wherein the crystallizer is a forced circulation crystallizer, draft tube baffle crystallizer, or any combination thereof [0064].
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Fang to incorporate the teachings of Wrubel to crystallize impurities from the neutralized filtrate in a first crystallization step in a forced circulation crystallizing step; crystallize impurities from the neutralized filtrate in a second crystallization step in a first draft tube crystallizing step; crystallize impurities from the neutralized filtrate in a third crystallization step in a second draft tube crystallizing step, because crystallizing in multiple steps is a process parameter well-known in the art of crystallization, as taught by Wrubel, in order to further improve the removal of impurities (i.e. potassium nitrate), absent a showing of unexpected results through routine experimentation (MPEP 2144.04 IV B).
Fang is further silent to precipitating remaining impurities via addition of a caustic material.
Fang, however, teaches carrying out a magnesium removing reaction to obtain magnesium hydroxide (a magnesium removing reaction to obtain magnesium hydroxide meets the limitation of precipitating remaining impurities; claim 1).
Hunwick discloses milk of lime (milk of lime meets the limitation of a caustic material) may be added to a blend of potassium, magnesium and lithium with chloride to precipitate the magnesium as insoluble magnesium hydroxide (magnesium hydroxide meets the limitation of an impurity) in order to remove magnesium, which can be a problem when present in high concentrations because both its sulphate and chloride are quite soluble in aqueous solutions [0109].
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Fang to incorporate the teachings of Hunwick to precipitate remaining impurities via addition of a caustic material in order to remove magnesium, which can be a problem when present in high concentrations because both its sulphate and chloride are quite soluble in aqueous solutions, as recognized by Hunwick [0109].
Claims 13 and 14 are rejected under 35 U.S.C. 103 as being unpatentable over Fang (CN 112758971) in view of Worsley (US 2015/0086452) and Nishikawa (JP 2022164547) and Wrubel (US 2015/0321924) and Hunwick (US 2021/0387860) and Gu (CN 101724748).
Regarding Claim 13, Fang, Worsely, Nishikawa, Wrubel, and Hunwick teaches the elements as described above with regards to claim 12.
Fang discloses a calcium-magnesium leaching solution of chemical ore dressing byproduct (pg. 8, paragraph 3).
Fang is silent to using sulfuric acid for acid leaching of the solids, and wherein a temperature of the acid leaching of the solids is between 75°C and 90°C.
Gu discloses acid leaching magnesium-containing ore using sulfuric acid (Abstract), wherein a temperature of the acid leaching of the ore is between 75°C and 80°C [0048].
Regarding the temperature of acid leaching in claim 13, between 75°C and 80°C taught by Gu meets the limitation of between 75°C and 90°C.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Fang to incorporate the teachings of Gu wherein acid leaching of the solids uses sulfuric acid, and wherein a temperature of the acid leaching of the solids is between 75°C and 90°C, because using sulfuric acid and temperatures between 75°C and 90°C for acid leaching are process parameters well-known in the art of acid-leaching magnesium-containing ore, as taught by Gu.
Regarding Claim 14, Fang discloses carrying out a magnesium removing reaction to obtain magnesium hydroxide (a magnesium removing reaction to obtain magnesium hydroxide meets the limitation wherein the precipitated impurity is magnesium hydroxide; claim 1).
Fang is silent to precipitating magnesium hydroxide with a caustic material, wherein the caustic material is milk-of-lime.
Hunwick discloses milk of lime may be added to a blend of potassium, magnesium and lithium with chloride to precipitate the magnesium as insoluble magnesium hydroxide in order to remove magnesium, which can be a problem when present in high concentrations because both its sulphate and chloride are quite soluble in aqueous solutions [0109].
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Fang to incorporate the teachings of Hunwick wherein the caustic material is milk-of-lime, and wherein the precipitated impurity is magnesium hydroxide in order to remove magnesium, which can be a problem when present in high concentrations because both its sulphate and chloride are quite soluble in aqueous solutions, as recognized by Hunwick [0109].
Claim 15 is rejected under 35 U.S.C. 103 as being unpatentable over Fang (CN 112758971) in view of Worsley (US 2015/0086452) and Nishikawa (JP 2022164547) and Wrubel (US 2015/0321924) and Hunwick (US 2021/0387860) and Gu (CN 101724748) and Rastas (US 6,274,104).
Regarding Claim 15, Fang, Worsley, Nishikawa, Wrubel, Hunwick, and Gu teach the elements as described above with regards to claim 14.
Fang discloses carrying out a magnesium removing reaction to obtain magnesium hydroxide (claim 1).
Fang is silent to recycling the magnesium hydroxide to neutralize the effluent slurry.
Rastas discloses precipitating magnesium hydroxide using calcium hydroxide (milk-of-lime is a calcium hydroxide solution and therefore precipitating magnesium hydroxide using calcium hydroxide meets the limitation of precipitating via the addition of milk-of-lime; Col. 8, lines 36-38), wherein the magnesium hydroxide can be reused as a neutralizing agent (Col. 1, line 67-Col. 2, line 1).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Fang to incorporate the teachings of Rastas wherein the magnesium hydroxide is recycled to neutralize the effluent slurry as magnesium hydroxide is a known neutralizing agent, as recognized by Rastas, and recycling is a well-known beneficial process which conserves resources.
Claim 17 is rejected under 35 U.S.C. 103 as being unpatentable over Fang (CN 112758971) in view of Worsley (US 2015/0086452) and Nishikawa (JP 2022164547) and Wrubel (US 2015/0321924) and Hunwick (US 2021/0387860) and Gu (CN 101724748) and Blei (US 2022/0356152).
Regarding Claim 17, Fang, Worsley, Nishikawa, Wrubel, and Hunwick teach the elements as described above with regards to claim 12.
Fang is silent to using Mechanical Vapor Recompression heated falling film evaporators to evaporate the neutralized filtrate at approximately 105°C.
Fang, however, discloses concentrating the neutralized liquid by evaporation at 100°C to 135°C (claim 6).
Regarding the evaporation temperature in claim 17, it appears that 100°C to 135°C taught by Fang overlaps the claimed value of 105°C such that the range taught by Fang obviates the claimed value. See MPEP 2144.05 (I).
Worsley discloses concentrating via evaporation (claim 1) by falling film MVR evaporators (falling film MVR evaporator meets the limitation of Mechanical Vapor Recompression heated falling film evaporator; claim 19, [0033]), which are evaporators known to have high rate of heat transfer and high energy efficiency (claim 19).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Fang to incorporate the teachings of Worsley wherein the Mechanical Vapor Recompression heated falling film evaporators evaporate the neutralized filtrate at approximately 105°C in order to evaporate with a high rate of heat transfer and high energy efficiency, as recognized by Worsley (claim 19).
Fang is further silent to the first crystallization step occurring at approximately 65°C; the second crystallization step occurring at approximately 40°C; and the third crystallization step occurring at approximately 10°C.
Fang, however, teaches crystallizing potassium nitrate at room temperature (pg. 6, paragraph 9), which is between the claimed values of 40°C for the second crystallization step and 10°C for the third crystallization step.
Blei discloses crystallization in three steps with decreasing temperatures from step to step, with the first step occurring at 70°C to 110°C, the second step occurring at 20°C to 70°C, and the third step occurring at -10°C to 25°C [0048].
Regarding the first crystallization step temperature in claim 17, it appears that 70°C to 110°C taught by Blei is close to the claimed value of 65°C such that the range taught by Blei obviates the claimed range. See MPEP 2144.05 (I).
Regarding the second crystallization step temperature in claim 17, it appears that 20°C to 70°C taught by Blei overlaps the claimed value of 40°C such that the range taught by Blei obviates the claimed range. See MPEP 2144.05 (I).
Regarding the third crystallization step temperature in claim 17, it appears that -10°C to 25°C taught by Blei overlaps the claimed value of 10°C such that the range taught by Blei obviates the claimed range. See MPEP 2144.05 (I).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Fang to incorporate the teachings of Blei wherein the first crystallization step occurs at approximately 65°C; the second crystallization step occurs at approximately 40°C; and the third crystallization step occurs at approximately 10°C, because decreasing temperatures from step to step when crystallizing in multiple steps is a process parameter well-known in the art of crystallization, as taught by Blei, in order to further improve the removal of impurities, absent a showing of unexpected results through routine experimentation (MPEP 2144.04 IV B).
Claim 18 is rejected under 35 U.S.C. 103 as being unpatentable over Fang (CN 112758971) in view of Worsley (US 2015/0086452) and Nishikawa (JP 2022164547) and Wrubel (US 2015/0321924) and Hunwick (US 2021/0387860) and Gu (CN 101724748) and Blei (US 2022/0356152) and Phinney (US 2011/0123420).
Regarding Claim 18, Fang, Worsley, Nishikawa, Wrubel, Hunwick, Gu, and Blei teach the elements as described above with regards to claim 17.
Fang is silent to cooling by water from a cooling tower in the crystallization step.
Phinney discloses a crystallizer is cooled by water from a cooling tower [0049].
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Fang to incorporate the teachings of Phinney wherein the second crystallization step is cooled by water from a cooling tower, because using water for cooling in crystallization is a process parameter well-known in the art of crystallization, as taught by Phinney.
Claims 19 and 20 are rejected under 35 U.S.C. 103 as being unpatentable over Fang (CN 112758971) in view of Worsley (US 2015/0086452) and Nishikawa (JP 2022164547) and Wrubel (US 2015/0321924) and Hunwick (US 2021/0387860) and Gu (CN 101724748) and Blei (US 2022/0356152) and Phinney (US 2011/0123420) and Morrison (US 4,409,253).
Regarding Claim 19, Fang, Worsley, Nishikawa, Wrubel, Hunwick, Gu, Blei, and Phinney teach the elements as described above with regards to claim 18.
Fang is silent to cooling by a glycol-water mixture in the crystallization step.
Morrison discloses a crystallization step is cooled with an ethylene glycol-water mixture (Col. 11, lines 59-61).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Fang to incorporate the teachings of Morrison wherein the third crystallization step is cooled with a glycol-water mixture, because using a glycol-water mixture for cooling in crystallization is a process parameter well-known in the art of crystallization, as taught by Morrison.
Regarding Claim 20, Fang is silent to cooling by a glycol-water mixture in the crystallization step, wherein the glycol mixture comprises ethylene glycol.
Morrison discloses a crystallization step is cooled with an ethylene glycol-water mixture (Col. 11, lines 59-61).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Fang to incorporate the teachings of Morrison wherein the glycol-water mixture comprises ethylene glycol, because using an ethylene glycol-water mixture for cooling in crystallization is a process parameter well-known in the art of crystallization, as taught by Morrison.
Response to Arguments
Applicant's arguments filed 8 December 2025 have been fully considered but they are not persuasive.
Applicant argues Fang’s silence does not imply that the lithium concentration is close to zero, and the absence of a disclosure of a substance does not necessarily mean that the disclosed substance is absent (“Remarks”, pg. 5, par. 2).
However, Fang discloses leaching low-grade phosphorite (pg. 4, par. 12-pg. 5, par. 1).
Gulbrandsen discloses the chemical composition of phosphorite includes SiO2, Al2O3, Fe2O3, MgO, CaO, Na2O, K2O, H2O, H2O−, TiO2, P2O5, CO2, SO3, F, organic matter, oil, and uranium (Abstract), such that phosphorite does not contain lithium and therefore, the neutralized filtrate of Fang does not contain lithium and crystallization of a lithium-potassium double salt is inherently avoided.
Alternatively, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Fang to incorporate the teachings of Nishikawa to hold the lithium concentration in the neutralized filtrate below a lithium target concentration to avoid crystallization (See alternative rejection of claim 1).
Conclusion
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/S.E.S./Examiner, Art Unit 1735
/PAUL A WARTALOWICZ/Primary Examiner, Art Unit 1735