SIMULATION-DRIVEN DEVELOPMENT FOR COARSE COMMINUTION PROCESS - A CASE STUDY OF GEITA GOLD MINE, TANZANIA USING PLANTSMITH PROCESS SIMULATOR

In different industries, separation (classification) is a typical process in processing bulk and granular materials. The mathematical model of the separation process based on theoretical mechanics and Markov chains’ theory was proposed. The model allows us to consider the sieve parameters, such as the tilt angle, the pitch and size of sieve orifices, and the material particles’ parameters such as size, friction coefficient, and initial velocity. Modeling the separation process allows us to justify the sieve parameters when the sieve is used effectively. The research methodology involved a comparison between model predictions and experimental data. The bulk material separation process’s intensity index on the sieve was calculated based on the experimental study results. Comparison between model data and experimental data indicates the adequacy of the proposed mathematical model of the separation process. The separator’s design elements are also offered, which will ensure the separation process’s high efficiency.

Absorption and stripping are opposites of each other, while extraction, membranes, chromatography, adsorption, and leaching are more specialty processes typically used for unique separation needs. Absorption is done to recover a valuable component in a gas stream for reuse or sale or the removal of a component in a gas stream to eliminate an environmental discharge. Solubility differences can be used to recover gases into liquids. A key difference between absorption and adsorption is that, in adsorption, the adsorbed material concentrates on the surface of the adsorbent as opposed to dissolving in a bulk liquid phase. There are a number of adsorbent materials used in this unit operation, including activated carbon, zeolites, and silica gel. Their surface chemistry pore size, and pore size distribution are controlled to maximize the adsorption of certain materials in preference to others.

“Kuroko” so called Black ore is a kind of complex polymetallic sulphide ore, the texture of which is very intimately associated with sulphide minerals such as copper, lead, zinc, iron etc. Numeraous deposits of the ore, which are widely distributed in the north-eastern district of Japan, are actually being mined and their output are concentrated by differential flotation processes. But, because of complexities in the nature of the ores, namely the variety of mineral content and mineral composition, fineness of mineralogical texture and tendency to oxidize easily, it is considerably difficult to obtain satisfactory separation of the costituent minerals.This article describes a general survey and some technical problems on the mill operations of the ores. The problems which were pointed out and reviewed by the author are as follows;(1) ore characteristics and processes of separation.(2) liberation of individual minerals.(3) processes for treatment of slime.(4) oxidation of ores.(5) flotation reagents used and elimination of their residual effects.(6) variation in grades and properties of feed ores and overall control of mill operation.

The Westinghouse AP1000™ nuclear power plant design uses several evolutionary and advanced components, systems and analysis methods in order to maximize plant operational safety and efficiency. One advanced component of the AP1000 is the integration of the MSHIM operation and control strategy within the plant design. As a summary, the MSHIM operation and control strategy is an operational philosophy that has evolved from the Constant Axial Offset Control (CAOC) strategy, which was originally developed for the current generation of Westinghouse PWRs. The term MSHIM is derived from the fact that reactivity control uses low worth (or gray) control rod banks as a “mechanical shim.” This is opposed to today’s PWRs, which depend largely on changes in the chemical shim (soluble boron) concentration in the reactor coolant in order to provide fine reactivity control. The MSHIM strategy is unique in that it makes use of two independently controlled rod groups to provide fine control of both the core reactivity and axial power distribution during a wide range of operational scenarios. In the AP1000, the MSHIM operation and control strategy has been fully integrated into the digital rod control system. Specifically, automatic control of core reactivity (or RCS temperature) is provided using four (4) banks of “gray” control rods and two (2) banks of traditional control rods, all moving in a defined overlap. Furthermore, automatic axial power distribution (i.e., ex-core ΔI) control is provided using a single, heavy bank of traditional control rods which move independently of the reactivity control banks. It has been demonstrated that fine control of core reactivity and axial power distribution control can be achieved during a wide range of operational scenarios while relying only upon the automatic rod control functionality. Changes in the concentration of the chemical shim within the reactor coolant can thus be limited to only that required to directly compensate fuel and/or burnable absorber depletion during a given fuel cycle. In the AP1000, the MSHIM operation and control strategy is complemented by the BEACON™ on-line core monitoring system. BEACON provides direct monitoring of power distribution related parameters such as departure from nucleate boiling ratio (DNBR), peak linear heat rate (PLHR), and shutdown margin (SDM). The integration of the BEACON monitoring system into the AP1000 plant increases operational flexibility by relaxing certain operational limits during BEACON operation. The net effect of BEACON integration, thus, is to maximize the ability of rod control under the MSHIM strategy to maintain reactor operation within the associated technical specification limits, even under adverse operational transients. This paper explores the robustness of the MSHIM operation and control strategy under a range of anticipated plant operational scenarios. Furthermore, this paper demonstrates the operational simplification associated with this strategy as it has been integrated into the AP1000 plant control systems.

Production of ceramic bricks with the required strength imposes significant restrictions on the process control of plastic shaping of the ceramic mixture in the auger extruder. It is due to several factors. Firstly, the certain nonstationarity of rheological properties of the source raw materials necessitates the automatic task-oriented changes in combinations of such values as shear rate, ceramic mixture moisture and vacuum pressure in the vacuum chamber of the extruder. To solve this problem it is necessary to maintain a coordinated control of the relevant automatic control systems of the electrical engineering complex. The second problem is the lack of technical tools to measure the values of shear rate in the pressure head of the extruder. And finally, the third factor is a necessity for monitoring and modeling of operating steps in brick production – from shaping to finished product output, that is a necessity to assess the impact of drying and firing processes on the possibility to make bricks of specified strength. The paper considers structural synthesis of the electrical engineering complex’ control system for plastic shaping of the ceramic mixture, including the problem of coordinated control: of the vacuum pump’ electrical drive, of the solenoid valve for water dosing, of the belt feeder’ electrical drives, of the mixer and the auger, as well as the use of digital observers of technological controlled coordinates and models in further phases of brick production.

An hourly modelling framework for the assessment of energy sources exploitation and energy converters selection and sizing in buildings

Investigation on pre-weakening and crushing of phosphate ore using high voltage electric pulses

Boundary value problems in transport with mixed and oblique derivative boundary conditions, steady state and transient solutions

Purpose. To improve the efficiency of fine particle classification in vibrating screens by determining the rational dynamic parameters of designs with spatial oscillations of the working body. Methods. A dynamic model of the vibrating screen was developed on the basis of the Lagrange equations of the second kind, taking into account mass, inertial, and elastic-damping characteristics. The amplitude–frequency characteristics were determined by the method of undetermined coefficients, while non-elastic resistances were considered according to Volterra’s principle. A parametric analysis of the influence of the screen geometry and exciter position was carried out using mathematical modelling and analytical relationships. The adequacy of the model was verified by comparison with known experimental data. Findings. For the first time, the influence of the mutual arrangement of the drive and the dimensions of the screen on the ratio of linear and angular displacements in systems with spatial oscillations has been substantiated. This makes it possible to purposefully form particle motion trajectories and optimise their transport velocity. It was shown that correct adjustment of the parameters reduces the risk of local overloads, ensures uniform loading of the screening surface, and increases the operational stability of the equipment. Originality. Dependencies of vibration amplitudes on the drive installation location and geometric parameters have been obtained. Regularities in the variation of the vibration displacement coefficient across the width of the screening surface have been determined. The proposed approach makes it possible to predict the behaviour of the working body under variable loading conditions and to formulate recommendations aimed at improving the efficiency of separation processes. Practical value. The developed recommendations can be used in the design of vibrating screens for the mining and mineral processing industry. Their application will contribute to increased productivity and selectivity, reduced energy consumption of processes, lower maintenance costs, and enhanced equipment reliability. The obtained conclusions are also useful for other industries where vibration technologies are applied, in particular for the processing of bulk construction materials and in the food industry.

Powering Reverse Osmosis (RO) systems with Renewable Energy (RE) is essential for decarbonising water production. Integration of RE requires large-scale RO plants to operate efficiently using variable power. Nevertheless, variable operation (involving matching the RO load to available power without battery back-up) has only been implemented for small-scale systems. This paper presents a variable-speed operation technique suitable for large-scale RO systems using an optimised operational strategy and a Model Predictive Controller (MPC). The technique was validated using a laboratory test rig having comparable performance to large-scale systems. A dynamic plant model was used to design the operational strategy and control system. Several operational strategies were explored for varying the operating parameters according to power available from a RE source. An advanced control system based on MPC was designed and compared to a conventional Proportional-Integral-Differential controller. The results showed that operation at variable recovery with constant brine flowrate delivered the lowest specific energy consumption and widest operation range for a system with an isobaric pressure exchanger. The MPC controller improved the settling time for a 10% step-change in permeate flowrate by 47%. Moreover, it improved energy utilisation, giving a 2.35% increase in hourly permeate production for a defined power input time-series.

Robust control of a SAG mill

Processes to separate bulk materials by grain size are widely used in the construction, chemical, mineral processing, and energy industries. The efficiency of the production process that uses the resulting powders often depends on the efficiency of the classification process. Therefore, improving the quality of finished powders based on modeling and improving their production technologies is a pressing issue. Modeling of classification processes in a separate stage and in a system of classifiers has been performed using a separation curve for a separate stage and the analyzed system of devices. A model has been developed for single-, dual-, and triple-row stage arrangements, with and without recirculation of non-target separation products. It has been shown that recirculation significantly improves the quality of the target products. Based on the obtained solutions, recommendations have been developed to improve the efficiency of bulk material separation processes in multi-stage classification systems. The proposed algorithm and calculation method allow us to find optimal schemes and operating modes of classifying multi-stage installations.

In this paper the development of a distributed control system for a wavelength and time-division multiplexed optical Customer Premises Network (CFN) is described. On the one side the constraints posed by the physical characteristics of the passive optical star network have been taken into account. On the other side the requirements arising from the applications are met. A third boundary condition is set by the ongoing international standardization of the B-ISDN. Means to cope with these boundary conditions are presented resulting in the design of a distributed equal peer control system which acts towards its environment as a B-ISDN NT2. The control system is based on the DSS1 protocol. It comprises the lower three OSI layers. The software has been specified in SDL. An outband control channel, based on fixed length cells is chosen. Quick channel setup and release times can be realized. The protocol provides the possibilities of logical addressing, user-user data transfer, privileges and bearer connection linking. With additional hardware, data channels with various bitrates can be switched, varying from 2.24 Mb/s up to the STM/sub 16/ payload capacity (2.4 Gb/s). The control system will be used in a demonstration CPN, which will be realized in 1991 as part of RACE project R1036. The initial application will be a television production environment, but the protocol is flexible enough to support a wide range of applications.

Decision supporting system for the design of control systems for distillation columns

The gas–liquid multiphase process plays a crucial role in the chemical industry, and the utilization of packed beds enhances separation efficiency by increasing the contact area and promoting effective gas–liquid interaction during the separation process. This paper primarily reviews the progress from fundamental research to practical application of gas–liquid multiphase processes in packed bed reactors, focusing on advancements in fluid mechanics (flow patterns, liquid holdup, and pressure drop) and the mechanisms governing gas–liquid interactions within these reactors. Firstly, we present an overview of recent developments in understanding gas–liquid flow patterns; subsequently we summarize liquid holdup and pressure drop characteristics within packed beds. Furthermore, we analyze the underlying mechanisms involved in bubble breakup and coalescence phenomena occurring during continuous flow of gas–liquid dispersions, providing insights for reactor design and operation strategies. Finally, we summarize applications of packed bed reactors in carbon dioxide absorption, chemical reactions, and wastewater treatment while offering future perspectives. These findings serve as valuable references for optimizing gas–liquid separation processes.