Papers by Keyword: Settling

Abstract: The active mining of the Mátraszentimre (Hungary) underground base-metal mine was halted in 1985. So far enormous research and efforts have been taken for the final closure of the mine. The technology of fly-ash based hydraulic backfilling was selected. About 95 000 tons of fly-ash backfilling is necessary to close the mine. A suitable technology have been developed, installed and put into operation. So far about 14 400 tons fly ash have been backfilled.This paper summarizes the main results and elements of the process engineering part of this work. The pozzolanic activity of fly-ash from the Mátra Power Station was examined in order to develop a new hydraulic binder with the addition of lime. As results of the different examinations it had been decided that the backfilling material should be lignite fly-ash from the tailings pond of the nearby Mátra Power Plant. The fly-ash hydraulic transport system of the Mátra Power Station was designed by our institute back in 1998. This system is still operating and now serving the material for backfilling. The knowledge of designing the power station pipeline system was utilized at designing the hydraulic backfilling system. The main technical parameters of the solid – liquid pipe flow were designed based on the Tarján – Faitli: coarse mixture flow in fine suspension flow model then and now as well. The design covered many other aspects of the task such as material characterization and mixing, settling behavior of the backfill, dewatering and mechanical properties of the backfill, water permeability and so on...

Abstract: Density and viscosity are two major rheological properties that determine the performance of an isopropyl laurate (IPL) ester based drilling fluid. In this study, the effect of barite particle size on the IPL drilling fluid system settling behaviour was investigated using five particle sizes namely-32, 32-45, 45-75, +75μm and the unsieved barite. Stokes’ law of separation theory was employed in the analysis. It was found that smaller barite particle sizes (<75μm) enhances the settling resistance. An ideal barite particle size of-32μm was chosen and used in the subsequent formulations to obtain optimum rheological properties by varying the amount of viscosifier used at 4.0, 10.0 and 20.0g marked as sample (a), (b) and (c). These samples were analysed for their rheology by using the conventional Fann viscometer calibrated using Bingham model. The results showed that sample (b) exhibited the most promising performance based on the plastic viscosity, yield point and gel strength rheological analyses. Moreover, IPL drilling fluid sample (b) showed improve particle suspension ability for more than 78 hours when compared to IPL drilling fluid system prepared using unsieved barite particles. The results suggested that palm oil based isopropyl laurate ester has the potential to be used as based fluid in the ester based drilling fluid system.

Abstract: The paper analyses the significance and value of the old building existing in today's society at first. And next, it expounds the relationship between the new and old building in modern society. And then, it analyzes the problems of the fusion of new and old building which exist in Yichang city during the process of city development. We are researching how to solve the problems of the fusion of new and old building in Yichang city by studying the current relatively successful example of retrofitting the old building in domestic and abroad, and hope it can provide references of the fusion methods of new and old building in the other cities.

Abstract: The influence of equiaxed crystal movements in a superheated environment on the melt kinetics of the equiaxed crystals was experimentally investigated by observation of the settling and melting behaviors of NH4Cl equiaxed crystals in its aqueous solution. The experimental set-up composed of the settling tubes, water bath and video capture device, where NH4Cl equiaxed crystals were acquired in a cooling zone and then introduced into the superheated settling tubes filling with NH4Cl-H2O model alloy, and the morphologies of the equiaxed crystals were video captured for further analysis. Two kinds of morphology evolution have been observed, and the difference was related with typical spinning movements of the equiaxed crystals during their sedimentation. Changes of the length of six primary dendrite arms have been measured; the results were compared with the calculated melting rate for equiaxed crystals without any convection. It has been shown that the convection induced by the sedimentation imposes a strong influence on the melting kinetics of the equiaxed crystals.

Abstract: This paper summarizes and reviews a number of important theoretical and experimental results connected to study of gravitational effects on liquid phase sintering. However, we will also investigate numerically gravity induced skeletal structure evolution during liquid phase sintering. Applying domain methodology, solid skeleton evolution will be introduced by definition of skeleton units determined by equilibrium dihedral angle and formation of large solid skeleton arranged in long chain of connected solid-phase domains. The settling procedure will be simulated by two submodels: free settling model in which solid-phase domains fall under gravity over already settled domains, and extended model in which settled domains continue their motion till they reach a position of their local equilibrium. Three more submodels will be also defined: rearrangement densification model, settling densification model, and Brownian motion model. It will be assumed that under gravity condition Stokes’s law settling usually dominates microstructure formation, where the settling procedure as well as settling time will be used for computation of average migration distance during defined time interval. Thus gravity induced solid-phase domain structure evolution will be simulated by simultaneous computation of displacement of the center of mass. The new methodology will be applied for simulation of microstructural evolution of a regular multi-domain model under gravity and gravity conditions.

Abstract: In the last two decades copper metallurgy has faced tough challenges to comply with environmental regulations and falling copper prices. Although in the last months copper price has increased, still the environmental issue and operation related costs remain and as long as foreseen they will continue to do so. To reduce emissions to the atmosphere and to shorten the converting cycle, most industrial processes, as well as emerging ones, are aiming at production of high matte grade. However, the increase in oxygen potential required by these processes results in highly oxidised slags with significant copper contents, which require their treatment for copper recovery. Despite the fact that long established slag cleaning processes perform reasonaby well for slags in the range 1.5% - 2.5% in copper, i.e. coexisting matte in the order 60% in copper content, they must be reconsidered when applying to slags equilibrating with high matte grades and/or white metal. The present study concentrates on the mechanism of copper losses into slags, its association to sulfur and oxygen, mainly, and methods for its recovery. Based on these considerations, high temperature liquid-liquid phase separation, i.e. Teniente type reactor, slag flotation and slag leaching methods technologies are discussed as specially applied in Chilean smelters. Also, a new approach based on material characteristics of both matte and slag, i.e. magnetic separation, is presented.