Evaluation of the Purity of Magnesium Hydroxide Recovered from Saltwork Bitterns

Liang

et al. 2023

Cryst. Res. Technol.

A continuous process for preparation of magnesium hydroxide with a forced circulation tubular reactor is proposed. The residence time distribution of the liquid in the reactor at different flow rates is measured, and the parameters of the tanks‐in‐series model are obtained. Using soluble magnesium salt and ammonia as raw materials, magnesium hydroxide is prepared. The effect of the flow rates on the product quality is investigated. The results show that the smaller the flow rate, the longer the residence time of the liquid in the reactor and the better the dispersion and crystal morphology of the products. When the total volume of the reactor is 300 mL and the flow rates are 5–50 mL min−1, the values of the average residence time of the liquid are 3094–351 s and the parameters of tanks‐in‐series model are 1.05–1.52. The reactors are closer to the continuous stirred tank reactor. The average particle sizes of the magnesium hydroxide products are 2.32–2.47 µm, and the values of I001/I101 are 1.17–0.89. The crystal morphology is flaky. Being compared with that from magnesium sulfate, the magnesium hydroxide products from magnesium nitrate have smaller particle size and better dispersibility.

Section: Introductionmentioning

confidence: 99%

Study on Preparation of Magnesium Hydroxide by Continuous Forced Circulation Process

Liang

et al. 2023

Cryst. Res. Technol.

ACS Sustainable Chem. Eng.

“…The metal salts (Na + , K + , and Mg 2+ ) of chloride (Cl − ) and sulfate (SO 4 generated as byproducts from solar salt production (∼10 million m 3 /year), desalination, and inorganic chemical processes. 11 The viable salt recovery technologies for recovering added-value components (salts) from these concentrated brines are still limited, and, in most cases, these mixed salt solutions/brines are rejected in the sea or other water bodies. 12 Variation in the solubility behavior of metal salts (Na + , K + , and Mg 2+ ) of chloride (Cl − ) and sulfate (SO 4 2−…”

Section: ■ Introductionmentioning

confidence: 99%

“…The metal salts (Na + , K + , and Mg 2+ ) of chloride (Cl – ) and sulfate (SO 4 2– ) have been chosen as the model systems (a total of six salts) for the study. The concentrated aqueous solution of these metal salts is generated as byproducts from solar salt production (∼10 million m 3 /year), desalination, and inorganic chemical processes . The viable salt recovery technologies for recovering added-value components (salts) from these concentrated brines are still limited, and, in most cases, these mixed salt solutions/brines are rejected in the sea or other water bodies …”

Section: Introductionmentioning

confidence: 99%

Process Design Framework for Inorganic Salt Recovery Using Antisolvent Crystallization (ASC)

Sahu,

Gao,

Bhatti

et al. 2023

Antisolvent crystallization (ASC) can be an alternative separation strategy over evaporative or cooling crystallization for selective salt recovery from aqueous salt mixtures. While a large amount of literature has been focused on phase equilibrium data generation, the implication of phase behavior on antisolvent selection and process performance has not been adequately discussed. This work aims to develop a methodical framework combining solubility behavior, phase balance, antisolvent selection, and solvent recovery to design sustainable ASC processes for the selective isolation of salts from aqueous solutions. The methodology was tested for the application of ASC to separate sodium sulfate from sodium chloride, as those mixtures generate as saline effluent from salt-harvesting activities. Technoeconomic feasibility, sustainability, and life cycle analysis of the proposed ASC process were performed to establish its potential toward commercialization. Several environmental impact categories were analyzed on the ASC process with antisolvent recovery, direct disposal, and incineration, comparing their performance and highlighting the overall sustainability. The presented process design framework will guide early feasibility studies considering ASC for inorganic salt separation and purification from saline effluents.

Crystal Growth & Design

“…A winning strategy is to extract magnesium in the form of magnesium hydroxide, Mg(OH) 2 , via reactive crystallization. , Magnesium hydroxide is a white and odorless compound extensively employed as (i) an excipient for pharmaceutical and nutraceutical products; (ii) an acidic waste neutralizer thanks to its adsorptive and coagulative properties, (iii) a precursor for magnesium oxide and magnesium carbonate production, and (iv) a smoke-suppressing flame-retardant agent in composite polymeric materials. , Depending on the industrial application, Mg(OH) 2 products must fulfill specific requirements. As an example, flame-retardant applications require Mg(OH) 2 hexagonal platelets characterized by an average particle size of ∼0.5 to 1.5 μm and a specific surface area of less than 10 m 2 /g .…”

Section: Introductionmentioning

confidence: 99%

The Role of Operating Conditions in the Precipitation of Magnesium Hydroxide Hexagonal Platelets Using NaOH Solutions

Romano,

Trespi,

Achermann

et al. 2023

Self Cite

Magnesium hydroxide, Mg(OH)2, is an inorganic compound extensively employed in several industrial sectors. Nowadays, it is mostly produced from magnesium-rich minerals. Nevertheless, magnesium-rich solutions, such as natural and industrial brines, could prove to be a great treasure. In this work, synthetic magnesium chloride and sodium hydroxide (NaOH) solutions were used to recover Mg(OH)2 by reactive crystallization. A detailed experimental campaign was conducted aiming at producing grown Mg(OH)2 hexagonal platelets. Experiments were carried out in a stirred tank crystallizer operated in single- and double-feed configurations. In the single-feed configuration, globular and nanoflakes primary particles were obtained, as always reported in the literature when NaOH is used as a precipitant. However, these products are not complying with flame-retardant applications that require large hexagonal Mg(OH)2 platelets. This work suggests an effective precipitation strategy to favor crystal growth while, at the same time, limiting the nucleation mechanism. The double-feed configuration allowed the synthesis of grown Mg(OH)2 hexagonal platelets. The influence of reactant flow rates, reactant concentrations, and reaction temperature was analyzed. Scanning electron microscopy (SEM) pictures were also taken to investigate the morphology of Mg(OH)2 crystals. The proposed precipitation strategy paves the road to satisfy flame-retardant market requirements.