硼酸快速流态化热分解制硼酸酐的新工艺

A NEW PROCESS OF PREPARING ANHYDROUS BORIC OXIDE BY DEHYDRATION OF BORIC ACID IN A FAST FLUIDIZED BED

本文针对硼酸热分解中易于粘结的技术难关,利用快速流态化具有传热、传质快和防止粘结的功能,提出了两段复合快速流化床、常压低温热气流连续热解脱水新工艺,以生产 B_2O_3含量大于99%的粉末状产品。与传统工艺相比,简化了工艺,降低了投资,节约能源,提高效率。该工艺亦适合其他物料的干燥脱水、热解、制粒等过程。

From the experiments of decomposition of boric acid,it is learned that at pressures above 1.9998 ×10~3 Pa.the dehydration of boric acid is always accompanied with the formation of liquid intermedi- ary metaboric acid HBO_(2).Thus,the product in form of a powder is too difficult to be produced in the atmosphere.Also,removal of the last traces of water from boric acid is not easy.Therefore,conven- tionally the preparation of anhydrous boric oxide was most often achieved by melting the sample under high vacuum. In the present work,a new process of preparing anhydrous boric oxide using air with limited rela- tive humidity as the drying medium has been proposed,which consists of a primary stage pre-dehydra- tion,corresponding to a conversion of about 60%,at 130 to 150℃ temperatures in a conventional fluidized bed and a secondary stage complete dehydration,approaching to a final conversion of 99% or more,at 200 to 230 C in a fast fluidized bed.As a result,due to increased gas-solid heat and mass transfer as well as stick-proof effect,the product,containing 99.2 to 99.6% B_2O_3 in form of a powder can be obtained.Compared to the conventional method,this process displays low investment,lower energy consumption and high production efficiency.