Zhang Weiguang

Research on activated alumina obtained by spray pyrolysis method

Activated Alumina was prepared by directly spray pyrolysis AlCl3 solution. Batch experiments was performed to choose better reaction device among muffle furnace, propane graphite furnace and tubular resistance furnace. The alumina was characterized by XRD and SEM, and the specific surface area of the prepared alumina was also examined. The experiment results showed that using the tubular resistance furnace by spray pyrolysis AlCl3 solution could effectively improve the efficiency of the pyrolysis, obviously change the morphology of product and effectively increase the specific surface area of product granule. Compared with the muffle furnace roasting, the product index of spray pyrolysis by using tubular resistance furnace was better, and the products conformed to the requirements of the index of activated alumina. The present paper provided a new way of preparing activated alumina.

A new green process to produce activated alumina by spray pyrolysis

Abstract A green process that uses the spray pyrolysis method to prepare activated alumina is proposed in this research. The effects of spray temperature, carrier gas pressure, and AlCl3 solution concentration are experimentally investigated using pure reagents. The products were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and specific surface area (BET) analyses. The results indicate that the spray temperature is the most important factor on the conversion ratio of alumina during the spray pyrolysis process. The conversion ratio of alumina achieved over 99% at the following optimal conditions: temperature of 1000°C, pressure of 0.3 MPa, and AlCl3 solution concentration of 10 wt%. The activated alumina with 8–20 nm particle size (γ-Al2O3+α-Al2O3) was prepared using the same process, which well met the requirement of the catalyst carrier. The green utilization of high-alumina fly ash and acid recycling can be achieved by using this process.

Characterization of Activated Alumina Production via Spray Pyrolysis

A novel method was developed to prepare activated alumina via spray pyrolysis of aluminum chloride solution. In this paper, activated alumina was obtained by spray pyrolysis in tube furnace with aluminum chloride solution as raw materials in different temperatures. X-ray diffraction (XRD), scanning electron microscope(SEM) and the specific surface area analysis were used to characterize the spray pyrolysis products, respectively. XRD results showed that the crystal phase composition of activated alumina can be controlled through adjusting pyrolysis temperature. The crystal structure of γ-Al2O3 in the products conformed to the requirements of the index of activated alumina. Most of pyrolysis products were porous structure which the particle size was around 5 μm under scanning electron microscope. With the activated alumina were examined by specific surface area analysis, the products existed as inkbottle-shaped and parallel-plate pores. Pyrolysis products more conformed to the requirements of activated alumina after examined by XRD, SEM, and the specific surface area.

Study on effective extraction of Al and Fe from high-iron bauxite through “calcification-carbonization” method

With the rapid development of China alumina production, efficient utilization of plentiful low grade high-iron bauxite has received widespread attention in the aluminum industry. Based on this, “calcification-carbonization-direct reduction” method is proposed for extracting effectively valuable metals Al and Fe from high-iron bauxite. The research results indicate that: after the calcification-carbonization process for high-iron bauxite, leaching rate of Al2O3 can reach 83.67%, higher than extraction rate of Al2O3 through Bayer method. Then, direct reduction of calcification-carbonization residue is investigated. Metallization ratio of Fe is 80.5% when reduction temperature and time is 1050°C and 2h respectively. Moreover, metallization ratio of Fe can reach 93.6% with the addition of additive A. After the “calcification-carbonization-direct reduction” process, valuable metals Al and Fe can be extracted effectively from high-iron bauxite. The main component of final residue is CaCO3 and CaSiO3, which can be directly applicable to the cement industry.