Lead–acid batteries are important to modern society because of their wide usage and low cost. The... more Lead–acid batteries are important to modern society because of their wide usage and low cost. The primary source for production of new lead–acid batteries is from recycling spent lead–acid batteries. In spent lead–acid batteries, lead is primarily present as lead pastes. In lead pastes, the dominant component is lead sulfate (PbSO4, mineral name anglesite) and lead oxide sulfate (PbO•PbSO4, mineral name lanarkite), which accounts for more than 60% of lead pastes. In the recycling process for lead–acid batteries, the desulphurization of lead sulfate is the key part to the overall process. In this work, the thermodynamic constraints for desulphurization via the hydrometallurgical route for recycling lead pastes are presented. The thermodynamic constraints are established according to the thermodynamic model that is applicable and important to recycling of lead pastes via hydrometallurgical routes in high ionic strength solutions that are expected to be in industrial processes. The the...
14 In this study, solubility measurements on tri-calcium di-citrate tetrahydrate 15 [Ca3[C3H5O(CO... more 14 In this study, solubility measurements on tri-calcium di-citrate tetrahydrate 15 [Ca3[C3H5O(COO)3]2•4H2O, abbreviated as Ca3[Citrate]2•4H2O] as a function of ionic 16 strength are conducted in NaCl solutions up to I = 5.0 mol•kg and in MgCl2 solutions 17 up to I = 7.5 mol•kg, at room temperature (22.5 ± 0.5C). The solubility constant 18 ( 0 log sp K ) for Ca3[Citrate]2•4H2O and formation constant ( 0 1 log ) for Ca[C3H5O(COO)3] – 19 , 20 21 Ca3[C3H5O(COO)3]2•4H2O (earlandite) = 3Ca + 2[C3H5O(COO)3] + 4H2O (1) 22 23 Ca + [C3H5O(COO)3] = Ca[C3H5O(COO)3] (2) 24 25 are determined as –18.11 ± 0.05 and 4.97 ± 0.05, respectively, based on the Pitzer model 26 with a set of Pitzer parameters describing the specific interactions in NaCl and MgCl2 27 media. 28 The solubility measurements and thermodynamic modeling indicate that 29 Ca3[Citrate]2•4H2O could become a solubility-controlling phase for citrate in geological 30 repositories for nuclear waste when the inventories of citrate reach...
In previous studies on Am(III)/Nd(III) interactions with borate, the borate concentrations were... more In previous studies on Am(III)/Nd(III) interactions with borate, the borate concentrations were kept at a relatively low level, up to ~0.16 mol•kg as the highest. Such concentrations of borate are not saturated, in terms of borate, with borate-bearing phases such as borax (Na2B4O7•10H2O) and tincalconite (Na2B4O7•5H2O) that could be present in geological repositories. For instance, tincalconite has been observed as a corrosion product for boroslicate glass for HLW under the repository conditions in China. In this study, we examine the Nd(III) interactions with borate in equilibrium with borax in a wide range of NaCl solutions at 25C. In our experiments, the solubility-controlling phase for Nd(III) is Nd(OH)3(micro cr). In synthesis of Nd(OH)3(micro cr), we followed the procedure from literature. Our results indicate that high borate concentrations (~0.5 mol•kg) in 0.01 and 0.1 mol•kg NaCl solutions have an obvious effect on Nd(III). At such a high concentration of borate, borate c...
The Fracture-Matrix Transport (FMT) code developed at Sandia National Laboratories solves chemica... more The Fracture-Matrix Transport (FMT) code developed at Sandia National Laboratories solves chemical equilibrium problems using the Pitzer activity coefficient model with a database containing actinide species. The code is capable of predicting actinide solubilities at 25 °C in various ionic-strength solutions from dilute groundwaters to high-ionic-strength brines. The code uses oxidation state analogies, i.e., Am(III) is used to predict solubilities of actinides in the +III oxidation state; Th(IV) is used to predict solubilities of actinides in the +IV state; Np(V) is utilized to predict solubilities of actinides in the +V state. This code has been qualified for predicting actinide solubilities for the Waste Isolation Pilot Plant (WIPP) Compliance Certification Application in 1996, and Compliance Re-Certification Applications in 2004 and 2009.We have established revised actinide-solubility uncertainty ranges and probability distributions for Performance Assessment (PA) by comparing a...
Magnesium oxide (MgO) is the only engineered barrier certified by the EPA for emplacement in the ... more Magnesium oxide (MgO) is the only engineered barrier certified by the EPA for emplacement in the Waste Isolation Pilot Plant (WIPP), a U.S. Department of Energy repository for transuranic waste. MgO will reduce actinide solubilities by sequestering CO2 generated by the biodegradation of cellulosic, plastic, and rubber materials. Demonstration of the effectiveness of MgO is essential to meet the U.S Environmental Protection Agency's requirement for multiple natural and engineered barriers. In the past, a series of experiments was conducted at Sandia National Laboratories to verify the efficacy of Premier Chemicals LLC (Premier) MgO as a chemical-control agent in the WIPP. Since December 2004, Premier MgO is no longer available for emplacement in the WIPP. Martin Marietta Magnesia Specialties LLC is the new MgO supplier. MgO characterization, including chemical, mineralogic, and reactivity analysis, has been performed to address uncertainties concerning the amount of reactive cons...
The Waste Isolation Pilot Plant (WIPP) is a U.S. Department of Energy (DOE) repository in southea... more The Waste Isolation Pilot Plant (WIPP) is a U.S. Department of Energy (DOE) repository in southeast New Mexico for defense-related transuranic (TRU) waste. The repository, which opened in March 1999, is located at a subsurface depth of 655 m (2150 ft) in the Salado Fm., a Permian bedded-salt formation. The repository will eventually contain the equivalent of 844,000 208 L (55 gal) drums of TRU waste. After filling the rooms and access drifts and installing panel closures, creep closure of the salt will crush the steel waste containers in most cases and encapsulate the waste. The WIPP actinide source term model used for long-term performance assessment (PA) of the repository comprises dissolved and suspended submodels (solubilities and colloids). This presentation will describe the solubilities. From the standpoint of long-term PA, the order of importance of the radioelements in the TRU waste to be emplaced in the WIPP is Pu ~ Am >> U > Th >> Np ~ Cm and fission produc...
Lead–acid batteries are important to modern society because of their wide usage and low cost. The... more Lead–acid batteries are important to modern society because of their wide usage and low cost. The primary source for production of new lead–acid batteries is from recycling spent lead–acid batteries. In spent lead–acid batteries, lead is primarily present as lead pastes. In lead pastes, the dominant component is lead sulfate (PbSO4, mineral name anglesite) and lead oxide sulfate (PbO•PbSO4, mineral name lanarkite), which accounts for more than 60% of lead pastes. In the recycling process for lead–acid batteries, the desulphurization of lead sulfate is the key part to the overall process. In this work, the thermodynamic constraints for desulphurization via the hydrometallurgical route for recycling lead pastes are presented. The thermodynamic constraints are established according to the thermodynamic model that is applicable and important to recycling of lead pastes via hydrometallurgical routes in high ionic strength solutions that are expected to be in industrial processes. The the...
14 In this study, solubility measurements on tri-calcium di-citrate tetrahydrate 15 [Ca3[C3H5O(CO... more 14 In this study, solubility measurements on tri-calcium di-citrate tetrahydrate 15 [Ca3[C3H5O(COO)3]2•4H2O, abbreviated as Ca3[Citrate]2•4H2O] as a function of ionic 16 strength are conducted in NaCl solutions up to I = 5.0 mol•kg and in MgCl2 solutions 17 up to I = 7.5 mol•kg, at room temperature (22.5 ± 0.5C). The solubility constant 18 ( 0 log sp K ) for Ca3[Citrate]2•4H2O and formation constant ( 0 1 log ) for Ca[C3H5O(COO)3] – 19 , 20 21 Ca3[C3H5O(COO)3]2•4H2O (earlandite) = 3Ca + 2[C3H5O(COO)3] + 4H2O (1) 22 23 Ca + [C3H5O(COO)3] = Ca[C3H5O(COO)3] (2) 24 25 are determined as –18.11 ± 0.05 and 4.97 ± 0.05, respectively, based on the Pitzer model 26 with a set of Pitzer parameters describing the specific interactions in NaCl and MgCl2 27 media. 28 The solubility measurements and thermodynamic modeling indicate that 29 Ca3[Citrate]2•4H2O could become a solubility-controlling phase for citrate in geological 30 repositories for nuclear waste when the inventories of citrate reach...
In previous studies on Am(III)/Nd(III) interactions with borate, the borate concentrations were... more In previous studies on Am(III)/Nd(III) interactions with borate, the borate concentrations were kept at a relatively low level, up to ~0.16 mol•kg as the highest. Such concentrations of borate are not saturated, in terms of borate, with borate-bearing phases such as borax (Na2B4O7•10H2O) and tincalconite (Na2B4O7•5H2O) that could be present in geological repositories. For instance, tincalconite has been observed as a corrosion product for boroslicate glass for HLW under the repository conditions in China. In this study, we examine the Nd(III) interactions with borate in equilibrium with borax in a wide range of NaCl solutions at 25C. In our experiments, the solubility-controlling phase for Nd(III) is Nd(OH)3(micro cr). In synthesis of Nd(OH)3(micro cr), we followed the procedure from literature. Our results indicate that high borate concentrations (~0.5 mol•kg) in 0.01 and 0.1 mol•kg NaCl solutions have an obvious effect on Nd(III). At such a high concentration of borate, borate c...
The Fracture-Matrix Transport (FMT) code developed at Sandia National Laboratories solves chemica... more The Fracture-Matrix Transport (FMT) code developed at Sandia National Laboratories solves chemical equilibrium problems using the Pitzer activity coefficient model with a database containing actinide species. The code is capable of predicting actinide solubilities at 25 °C in various ionic-strength solutions from dilute groundwaters to high-ionic-strength brines. The code uses oxidation state analogies, i.e., Am(III) is used to predict solubilities of actinides in the +III oxidation state; Th(IV) is used to predict solubilities of actinides in the +IV state; Np(V) is utilized to predict solubilities of actinides in the +V state. This code has been qualified for predicting actinide solubilities for the Waste Isolation Pilot Plant (WIPP) Compliance Certification Application in 1996, and Compliance Re-Certification Applications in 2004 and 2009.We have established revised actinide-solubility uncertainty ranges and probability distributions for Performance Assessment (PA) by comparing a...
Magnesium oxide (MgO) is the only engineered barrier certified by the EPA for emplacement in the ... more Magnesium oxide (MgO) is the only engineered barrier certified by the EPA for emplacement in the Waste Isolation Pilot Plant (WIPP), a U.S. Department of Energy repository for transuranic waste. MgO will reduce actinide solubilities by sequestering CO2 generated by the biodegradation of cellulosic, plastic, and rubber materials. Demonstration of the effectiveness of MgO is essential to meet the U.S Environmental Protection Agency's requirement for multiple natural and engineered barriers. In the past, a series of experiments was conducted at Sandia National Laboratories to verify the efficacy of Premier Chemicals LLC (Premier) MgO as a chemical-control agent in the WIPP. Since December 2004, Premier MgO is no longer available for emplacement in the WIPP. Martin Marietta Magnesia Specialties LLC is the new MgO supplier. MgO characterization, including chemical, mineralogic, and reactivity analysis, has been performed to address uncertainties concerning the amount of reactive cons...
The Waste Isolation Pilot Plant (WIPP) is a U.S. Department of Energy (DOE) repository in southea... more The Waste Isolation Pilot Plant (WIPP) is a U.S. Department of Energy (DOE) repository in southeast New Mexico for defense-related transuranic (TRU) waste. The repository, which opened in March 1999, is located at a subsurface depth of 655 m (2150 ft) in the Salado Fm., a Permian bedded-salt formation. The repository will eventually contain the equivalent of 844,000 208 L (55 gal) drums of TRU waste. After filling the rooms and access drifts and installing panel closures, creep closure of the salt will crush the steel waste containers in most cases and encapsulate the waste. The WIPP actinide source term model used for long-term performance assessment (PA) of the repository comprises dissolved and suspended submodels (solubilities and colloids). This presentation will describe the solubilities. From the standpoint of long-term PA, the order of importance of the radioelements in the TRU waste to be emplaced in the WIPP is Pu ~ Am >> U > Th >> Np ~ Cm and fission produc...
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