Bo Lin Wu

Preparation of Merwinite with Apatite-Forming Ability by Sol-Gel Process

Merwinite powders were synthesized by a sol-gel process. The bioactivity in vitro of merwinite was investigated by soaking the powders in simulated body fluid (SBF), the growth of hydroxyapatite(HAp) on the surface of the powder was evaluated in various time. It was found that hydroxyapatite was formed after soaking for 14 days. The results indicate that merwinite possessed apatite-formation ability might be a potential candidate biomaterial for hard tissue repair.

Effect of Barium Aluminates on Acid Resistance of Fracturing Proppants

In order to explore the effect of removing siliceous components on acid resistance of fracturing proppants, acid resistance of fracturing proppants in a new silicon-free system was studied in this paper. The fracturing proppants were made by pressureless sintering using high-purity alumina and barium carbonate as the basic raw material. Acid resistance test was carried out in 12 wt% HCl + 3 wt% HF at 65 oC for 30 minutes according to The Petroleum and Gas Industrial Standards of China (SY/T5108-2006) and morphology, structure and chemical analysis of the samples were investigated using X-ray diffraction and scanning electron microscopy. Experiments show that fracturing proppants that contain barium aluminates have better acid resistance. The acid solubility of the samples is less than 3%, especially when the content of barium carbonate is about 10% (mass fraction, the same below), the acid solubility of the sample reaches 0.52% which is far beyond the demands (5%) of the Standards of SY/T5108-2006. Results prove that the removal of siliceous components of raw materials can prominently improve the acid resistance of fracturing proppants. It can provide a new referential thought for improving the acid resistance of fracturing proppants.

Extraction of Valuable Metals from Red Mud

The reason of comprehensive utilization of red mud is that it contains recycled oxides and a variety of valuable metals. In this paper, the basic characterization of red mud is described. The current developments of extraction of Fe, Ti, Sc, rare earth and valuable metals from red mud are summarized with some emphasis. In addition, the technological features of each process route are analyzed briefly. It can be concluded that it is practiable to extract Fe, Ti, Sc, rare earth and valuable metals from red mud. However, in order to realize recycling of red mud, the key is that an economic, energy saving, environment friendly and widely applicable process has to be found.

Comprehensive Utilization of Red Mud Remaining in Alumina Production

Red mud is a solid waste which is generated in the process of alumina production and is of highly alkaline. Red mud has very complex compositions, but contains a variety of rare and valuable metals. In addition, its high alkalinity is a severe pollution to water, land, air and environment, which has been one of the main factors to affect the sustainable development of aluminum industry. The characterization of red mud, the extraction of valuable metals from red mud, the utilization of red mud in construction materials, environmental restoration materials and other fields are introduced in this paper.

Crystal Structure and Chemical Composition of BIMEVOX (ME=Mn)

The Bi2MnxV1-xO5.5- powders were synthesized by high temperature melting method. The effect of Mn dopant concentration on the crystal structure and chemical composition was studied. The crystal structure was determined by X-ray powder diffraction. The chemical composition was tested by X-ray fluorescence (XRF) and Energy Disperse Spectroscopy (EDS). When x < 0.2 the Aurivillius structure solid solution coexisted with few BiVO4. When 0.2 ≤ x ≤ 0.3 the γ-phase Bi2MnxV1-xO5.5- solid solution with tetragonal structure formed and the maximum Mn atomic content was 2.14%. When x ≥ 0.4 the manganese oxide secondary phase appeared. And when x = 0.8 the Bi7VO13 structure solid solution formed while the Aurivillius structure disappeared.

Phase Transition Activity Characteristics of Nanosized AlOOH in the Hydrothermal Synthesis of Nanosized α-Al2O3

α-Al2O3 nanopowders were prepared by a novel synthesis process, using the nanosized α-Al2O3 obtained from pyrolyzing ammonium aluminum carbonate hydroxide as seeds and the self-dispersed nanosized AlOOH crystal powders as precursors. Based on their good self-dispersion in water, the α-Al2O3 seeds were dispersed evenly into the AlOOH sol by the new homodispersion mixing technique. This process enables the conversion of AlOOH to alumina at 190°C (hydrothermal temperature), in which the alumina is calcined to nanosized alpha-alumina having an average length to diameter ratio of 60nm:15nm at 930°C. In the synthesis reaction for transforming the AlOOH to alumina, the effect of superfine pulverization and self-dispersion of the precursors was studied.

Preparation of High-Purity α-Alumina by Oil-in-Water Microemulsion

The main objective of this work was to prepare high purity α-alumina powder (α-Al2O3) by mixed oil-in-water microemulsion route. In this study α-alumina was prepared by quaternary microemulsion system (water/surfactant/co-surfactant/oil-phase). OP-10, alcohol and the mixed solution of cyclohexane and aluminium isopropoxide were used as surfactant, co-surfactant and oil-phase, respectively. After drying the amorphous precursor powder, α-alumina powder is obtained by sintering at 1200°C for 3-5h. The X-ray diffraction pattern shows the presence of alumina phase with crystal structure and the slow scan with step size 0.0170°/sec of selected diffraction peaks such as (113) has been recorded and calculated by Scherer’s formula. The average crystallite size is about 40nm.

Preparation of Self-Releasing Glaze Ceramic Materials Utilizing Red Mud

Red mud is the main solid residue generated during the production of alumina by means of the Bayer process. In order to expand the comprehensive utilization field of red mud and develop new ceramic products with low radioactivity utilizing red mud, the exploration of preparing self-releasing glaze ceramic materials using red mud as raw material was carried out. During the exploration, the self-releasing glaze ceramic materials with low radiation level were produced by normal pressure sintering process using the main ingredients of red mud, red sandstone, barium carbonate and ball clay. The properties of the self-releasing glaze ceramic samples were investigated by the measurements of mechanical properties, X-ray diffraction (XRD), scanning electron microscopy (SEM) and radiation measurement. The results show that the self-releasing glaze ceramic materials have good mechanical properties (the bulk density, 3.10 g/cm3; the compressive strength, 78.00 MPa). Adding barium carbonate to the raw materials and then calcine them to ceramics, which can extend the sintering temperature range and the radioactivity level of the self-releasing glaze ceramic materials can be reduced to that of the natural radioactive background of Guilin Area, Karst landform (the average 60 Total/Timer).

Preparation of the System of BaO-MgO-Al2O3-TiO2 Acid-Resistant Fracturing Proppants

In order to improve the acid resistance and reduce the apparent density of fracturing proppants, TiO2 powder added in the system of BaO-MgO-Al2O3 fracturing proppants were prepared by the technique of pressureless sintering. The properties of the samples were investigated by the measurements of acid solubility, X-ray diffraction and scanning electron microscopy. The results show that the acid solubility of alumina matrix fracturing proppants contenting TiO2 of the 4wt% and BaO/MgO with the ratio of 3:7 is 0.15%. It is an important development in acid resistance performance of fracturing proppants research on laboratory. TiO2 is added to the raw materials and then calcine them to ceramics, which can reduces the sintering temperature, promote the densification and improve acid-resistant property of fracturing proppants.

Preparation and Characteristics of BiFeO3 Ceramics Doped by MnO2 and Co2O3

BiFeO3-based single-phase multiferroics have been widely studied in both ceramics and films. However, the macroscopic magnetic properties of BiFeO3 ceramics were now most very weak. In this work, MnO2 and Co2O3 were used as B-site substitutes in BiFeO3 ceramics in order to the enhancement of magnetic properties. The change of magnetization was analyzed based on the phase composition and the microstructure of ceramics.