The Extraction Technology Research Of Lithium And Magnesium In Concentrated Seawater And Brine

Firstly, the leached type Mg(OH)2was prepared with brine and ammonia as raw material. Secondly, the basic magnesium sulfate whiskers were synthesized via hydrothermal synthesis using magnesium sulfate solution and self-maded Mg(OH)2as reactants. The effects of whiskers length to diameter ratio that material ratio, reaction time, reaction temperature and the concentration on magnesium sulfate solution were investigated in experiment. Chemical analysis, SEM, XRD, TG-DTG were performed for analysis of basic magnesium sulfate whiskers. The basic magnesium sulfate whiskers were modified by surface modification agents such as KH-550, stearic acid, sodium dodecyl benzene sulfonate, sodium stearate, potassium oleate and so on. The experimental results are as follows:the raw material ratio of Mg(OH)2:MgSO4was1:4, the time of reaction was4h, the temperature of the reaction was190℃, the concentration of magnesium sulfate solution was0.3mol·L-1. The prepared whiskers with diameter1～2μm, length200-300μm, aspect ratio150-250was fan. The composition of synthesed basic magnesium sulfate whiskers were MgSO4·5Mg(OH)2·2H2O. With potassium oleate to basic magnesium sulfate whiskers surface treatment, a good surface modification effect can be achieved, with the oil-wet coefficient value of the modified basic magnesium sulfate whiskers reaching0.55.Magnesium hydrate whiskers were prepared via hydrothermal synthesis using basic magnesium sulfate whiskers and sodium hydroxide as reactants. The optimal experimental condition has been attained by experiment:the raw material ratio of MHSH:NaOH was1:2, the temperature of the reaction was200℃, the time of reaction was3h, pulp concentration was4(wt)%, the concentration of sodium hydroxide was0.3mol·L-1. SEM, XRD, TG-DTG were performed for analysis of magnesium hydrate whiskers. The prepared whiskers with diameter1～2μm, length100～200μm, aspect ratio100～200was fan. Magnesium hydrate whiskers were modified by surface modification agents such as KH-550, stearic acid, sodium dodecyl benzene sulfonate, sodium stearate, potassium oleate and so on. The results indicate that using the potassium oleate as surface modification agent. At potassium oleate dosage of5(wt)%, a good surface modification effect can be achieved, with the activation index of the modified magnesium hydrate whiskers reaching99.48%.The granular-type Li4Mn5O12adsorbent was prepared using PVC as a binder, KCl as a porogen and was then changed to H type ion-sieve by proper dilution with HCl solution. The prepared granular adsorbent was characterized by SEM and static/dynamic adsorption-desorption measurement and saturated adsorption capacity, the effect of different concentration of eluent on stripping performance and stripping rate were measured. The results showed that static adsorption kinetics of granular adsorbent is well accorded with Lagergren equation and the adsorption rate constant is9.99×10-6s-1,respectively,the staticion-exchange capacity for lithium ions is2.40mmol·g-1. Experiment results have good correlation.The lithium adsorption capacity of granular lithium-ion sieve in pure solution of lithium was measured. The elution was carried out by different concentrations of HCl. The greater the concentration of hydrochloric acid, the higher the concentration of lithium ions in the effluent. When the hydrochloric acid concentration is less than0.02mol· L-1, elution curve has been turned into an approximation of a smooth curve. Elution rate increases as the hydrochloric acid concentration increases.