Synthesis Of New Boron Extractant And Adsorbent, And Extracting Boron From Pingluo Underground Brine Located In Sicuan Basin

Pingluo underground brine located in Sichuan Basin is rich in potassium,lithium,boron,rubidium and other elements,among which the content of potassium and boron elements is as high as 53.3 g/L and 4.99 g/L respectively,exceeding a lot the industrial mining grade and containing considerable mining value.The traditional exploitation technology entails a huge loss of boron in the sodium and potassium precipitation stage,resulting in an unsatisfactory recovery rate of boron and a waste of resources.To solve this problem,this paper adopts the solvent extraction method to isolate the majority of boron from brine before the potassium extraction process and generate corresponding boronic acid products.In the post stage of brine comprehensive utilization,the small amount of remaining boron is concentrated in the old brine and can be recovered fully through the absorption method.To this end,this paper carries out studies about the new boron extraction agent,the new boron absorbent and boron extraction technology for Pingluo underground brine,and boron absorption process.Research results offer a scientific reference for the comprehensive utilization of brine rich in potassium and boron in Pingluo.1.Synthesis of new boron extraction agent.Formaldehyde and isobutyraldehyde were used as raw materials,triethylamine as catalyst to prepare 2-dimethyl-propionic aldehyde.Under the protection of N₂,2-dimethyl-propionic aldehyde was reduced to the extraction agent 2,2,4-trimethylpentane-1,3-diylbis through Grignard reagent sec-butyl magnesium bromide.The extraction agent is insoluable in diluents commonly used for boron solvent extraction,such as kerosene,sulfonated kerosene,toluene and the like,and is easily soluble in chloroform.2.Study of Pingluo brine boron extraction process.The experiment of boron extraction was completed by a centrifugal extractor.The boron extraction rate of 0.8mol/L 2,2,4-trimethylpentane-1,3-diylbis from Pingluo brine was 64%,lower than expected.In comparison,the mixed alcohol system in the experimental group obtained a higher extraction rate.The mixed alcohol system was composed of2-Ethyl-1,3-hexanediol,isooctyl alcohol and sulfonated kerosene by a volume ratio of2:3:5.If the mixed alcohol was used as the extraction agent,the extraction rate could reach 97%by adjusting the experimental conditions,and the re-extraction rate is 95%.Through the continuous extraction experiments on mixed alcohol,it is found that the mixed alcohol can be reused repeatedly while maintaining a high extraction rate.3.Synthesis of new boron absorbent.The absorption method is commonly used for boron extraction.However,the difference is that this method is often used in circumstances where the boron concentration is relatively low.In this paper,glycidyl methacrylate?GMA?,ethylene glycol dimethacrylate?EGDMA?,N-Methyl-D-glucamine?NMDG?were used as key raw materials to obtain GMA-EGDMA copolymers through suspension polymerization of GMA and EGDMA under certain conditions,and then obtain GMA-EGDMA copolymer NMDG by using the glycidyl and NMDG reaction on the copolymers.4.Experiment of boron extraction process through absorption method.In the static experiment of new absorbent,used the Pingluo underground brine as mother liquor,the extract liquor contain 830 mg/L boric acid after 3-level mixed alcohol extraction.At a temperature of 40°C and pH value of 8,absorption can reach equilibrium after three hours.The saturated adsorption capacity is 45.50 mg/g?calculated by boric acid?after several times of absorption.In addition,a 0.15 mol/L hydrochloric acid was used for the elution of negative boron absorbent;the elution rate is 92%.