Study on mixing and segregation behaviors in particulate fluidized bed system for mineral processing

In order to identify the mixing and segregation behaviors in a mineral processing operation, present study aimed on the hydrodynamics of solid–liquid fluidization. The study was carried out in a fluidization column with tapings at different height of the bed to collect the sample. The binary particles considered in this study are hematite(4800 kg/m3) and quartz(2600 kg/m3) at different size fractions in the range of average size 87×10^(-6)m to 400×10^(-6)m. It is observed that for various binary mixtures, both quartz and hematite particles share the equal composition by mass(50%) at a particular height of fluidized bed, referred as ‘‘locus point'' of mixing. Study indicates that the mixing zone volume will increase for a continuous fluidized bed plant operation. It is observed that the number of locus points varies from 1 to 3 signifying their dependency on the size ratios of binary mixture. Whenever, the difference in terminal velocity between quartz and hematite particles approaches to zero, mixing is enhanced.Further, the present study is extended to find the segregation index for the different size ratios of quartz and hematite particles. It is evident that depending on the size ratios, various regions such as complete segregation, partial mixing and complete mixing can be observed.

Kinetic of Dissolved Phosphorus from Calcination Products of Mixed Rare Earth Minerals

The products of mixed rare earth minerals containing monazite and bastnaesite calcined by CaO-NaCl-CaCl2 contained calcium phosphate and phosphorite. In this paper, HCl-H3cit solution was used to wash the calcination products, and the kinetic character of dissolved phosphorus was studied. The results showed that the reaction rate control changed from chemical reaction control mode to mixed control mode and diffusion control mode with increasing temperature, and the activation energy were 7.36, 27.64 and 61.27 kJ·mol-1, respectively. The change of temperature, the reagent concentration and stirring speed were studied in order to increase the dissolution rate of phosphorus. Phosphorus and rare earth in the calcination products could be separated in this process applicable to the rare earth recovery in phosphorite containing the rare earth.

Bioleaching of a kind of alkaline mixed copper oxide and sulphide mineral

We conducted two-stage acidification-bioleaching experiments to probe the feasibility of bioleaching for a kind of mixed alkaline copper oxide and sulphide mineral. We used the uniform design method for data analysis and experimental optimization, with initial pH value, pulp density, inoculation of bacteria and ferrous iron concentration selected as the influential factors. Polynomial regression shows that the four factors sequentially influence the copper recovery by 14.430%, 8.555%, 1.982% and 3.895%. Acid equilibrium in the bioleaching system is mainly influenced by alkaline gangue content, chemical reactions and bacterial activity. A maximal portion of refractory copper extracted reaches 71.08%. The dynamic analysis of copper recovery indicates that bioleaching goes through a lag leaching phase, prime leaching phase and leaching stationary phase corresponding to the growth phases of bacteria. Compared with the predicted value of 80.87%, the confirmatory experiment observes a 78.21% copper recovery under the optimal conditions of pH of 1.5, pulp density of 5%, bacteria inoculation of 30% and initial ferrous iron concentration of 9 g L-1. Results suggest that bioleaching is technically feasible to improving total copper recovery.

Comprehensive Recovery of Tin, Sulfur and Arsenic from Mixed Mineral of Tin, Sulfur and Arsenic

A mixed mineral of tin, sulfur and arsenic was studied in this paper. The main components of the mineral were separated and the physical parameters of each mineral were measured. Comprehensive recovery of tin, sulfur and arsenic from the mixed mineral was studied. A joint flowsheet of flotation and gravity was developed according to the mineralogical characteristics of the sample. Flotation was carried out first to produce sulfur concentrate while the tailing was processed by a second flotation to obtain rougher arsenic concentrate which was further processed by gravity separation to get arsenic concentrate and the tailing of gravity separation was processed to obtain tin concentrate.

Optimization of Cowpea Dry Grain Yield through the Stimulation of the RNA Synthetic Activity of NADH-Glutamate Dehydrogenase

Several potentially practical biochemical processes in plant systems still remain hidden, especially the NADH-glutamate dehydrogenase (GDH) synthesis of nongenetic code-based RNA that optimizes crop nutritious yield by degrading superfluous genetic code-based RNA. In continued characterization of the biochemistry of cowpea grain yield, GDH was purified by electrophoresis from seeds of cowpea treated with solutions of stoichiometric mixes of mineral salts. The GDH was made to synthesize RNAs in the amination (α-KG/NADH/) and then in the deamination (L-Glu/NAD+) direction. The initial product RNAs were captured and sequenced. The grand challenge was to discover the specific molecular roles of the redox enzyme in the optimization of cowpea grain yields. In the amination direction, the GDH hexamers synthesized plus-RNA, but in the deamination direction, they synthesized minus-RNA. The plus-RNAs and minus-RNAs were homologous to about the same numbers of different mRNAs encoding the key enzymes that regulate photosynthesis;saccharide biochemistry and glycolysis;phenylpropanoid biosynthesis;nodulation nitrogen fixing processes;dehydrin drought and glutathione environmental stress resistance processes;purine, pyrimidine, DNA, RNA and essential amino acid biosynthesis;storage protein vicilin accumulation;isoflavone earliness of cowpea maturity;peroxidase synthesis of lignin and sequestration of CO2 to enrich soil organic carbon contents;triglyceride physiology in the biosynthesis of bioactive compounds that render cowpea resistant to insects and fungi;etc., all of which constitute the GDH chemical pathways for discrimination of biochemical, physiological, metabolic, genetic reactions;and optimization of cowpea dry grain yields. Each stoichiometric mix of mineral salts produced optimally yielding biochemical variant of purple hull cowpea;the K + K + K mix was spectacular because it increased the grain yield to 7598 kg from the 3644 kg·ha-1 in the control cowpea. Optimized nutritious staple crop yield buttresses food security. The synthesis of plus-RNA in amination and minus-RNA in deamination is an economic tactical plan in biochemistry for the selection of superfluous mRNAs that would be degraded to assure the survival of cowpea growing under unfavorable environmental conditions.

Kinetics of mixed rare earths minerals decomposed by CaO with NaCl-CaCl_2 melting salt

For increasing reaction rate and reducing decomposing temperature,TG-DTA,XRD,SEM and Chemical analysis were used to study the kinetics of mixed rar e earths minerals decomposed by CaO with NaCl-CaCl2. The results showed that the reaction rate increased with increasing of NaC-CaCl2 addition,CaO addition,an d decomposition temperature. The kinetics of mixed rare earths minerals decompos ed by CaO conformed to 1-2/3X-(1-X) 2/3=kdt mode. The decomposition reaction rate was controlled by two steps,and the activation energy was decreased with addin g of NaCl-CaCl2 melting salt. The micro-pattern of products was loosening and po rous with NaCl-CaCl2 in decomposition system.