For most precious metal mines, cemented tailings backfill slurry (CTBS) with different cement-sand

ratio and solid concentration are transported into the gobs to keep the stability of the stope and mitigate

environmental pollution by mine tailing. However, transporting several kinds of CTBS through the same

pipeline will increase the risk of pipe plugging. Therefore, the joint impacts of cement-sand ratio and

solid concentration on the rheological characteristics of CTBS need a more in-depth study. Based on the

experiments of physical and mechanical parameters of fresh slurry, the loss of pumping pressure while

transporting CTBS with different cement-sand ratio, flux and solid mass concentration were measured

using pumping looping pipe experiments to investigate the joint impacts of cement-sand ratio and solid

concentration on the rheological characteristics of CTBS. Meanwhile, the effect of different stopped pumping

time on blockage accident was revealed and discussed by the restarting pumping experiments. Furthermore,

Fluent software was applied to calculate the pressure loss and velocity distribution in the pipeline to further

analysis experimental results. The overall trends of the simulation results were good agreement with the

experiment results. Then, the numerical model of the pipeline in the Sanshandao gold mine was conducted

to simulate the characteristics of CTBS pipeline transportation. The results show that the pumping pressure

of the delivery pump can meet the transportation requirements when there is no blockage accident. This

can provide a theoretical method for the parameters optimizing in the pipeline transportation system.

The paper presents the results of hydrogeological parameters determination carried out in the area of the Muschelkalk outcrop (Middle Triassic) near Tarnów Opolski. The studies consisted of a short pumping test in 16 piezometers and then their flooding and observation of water table recovery after the stopping of the pumping. The test allowed the values of hydraulic conductivity and specific capacity of Muschelkalk layers ranging from 8.56 · 10–8 m/s to 3.63 · 10–3 m/s and from 0.0075 to 128 m3/h/1mS, respectively, to be calculated. The wide range of values is related to the fact of studying the layers characterized by high permeability and water-bearing capacity (Karchowice Beds, Diplopora Beds and Górażdże Beds) as well as layers with low permeability (Gogolin Beds). The dense network of the research points made it possible to demonstrate the surface variability of rocks permeability and water- bearing capacity, determined mostly by the direction of outcrops of individual layers. The results of the conducted studies show that the most water-bearing zone of the area is related to the carbonate rocks of the Karchowice, Diplopora and Górażdże Beds, characterized by the highest values of hydraulic conductivity k (above 2 · 10–4 m/s) and specific capacity q (above 15 m3/h/1mS), in the belt stretching latitudinally through Kosorowice–Otmice. The studied area can be considered a Polish limestone-concrete field where several mines exploiting Muschelkalk carbonate rocks operate. The results of the conducted studies may be useful for the correct prognosis of the groundwater inflow either to already existing quarries or newly designed mines within the Major Groundwater Basins.

The unique oasis of Zousfana, on the western edge of the Grand Erg Occidental, Taghit is the pearl of the oases of Saoura, a palm grove of 180 ha over an 18 km length crossed by Oued Zouzfana. It regroups the different types of landscapes of an arid zone (erg, hamada, barga – a small hill, oued ...). Taghit is known for its hydraulic civilization, the oasis in its hostile environment has survived thanks to the exploitation of rare groundwater irrigation according to the traditional customs applied to the whole of society. The peasants spur out the water resources through foggaras and traditional wells. But the intervention of modern irrigation techniques in an anarchic way has disrupted the fragile mode of irrigation and the abandonment of the palm grove. The over-exploitation of groundwater by the use of boreholes and motor pumps leads to the drying up of water sources, mists and traditional wells. Today, only 45 000 palm trees are productive and less than 1500 fruit trees. There are 500 fellahs in the entire agricultural area of Taghit, the majority of them is fleeing work in the oasis because of the lack of income from it. When comparing the results of analyses from different campaigns (2015 and 2008), a spectacular increase in the salt concentrations in the groundwater of the different palm groves is noticed. According to our investigations, the main causes of this jump are: the overexploitation of the water tables by motor pumps, the abandonment of land inside the palm grove, the lack of maintenance of the gardens, the exploitation of domestic wastewater in the irrigation. According to this preliminary study, it is important for the State to make farmers aware of the role of their traditional irrigation systems in the continuity of the oasis and life in it.

This paper extends knowledge about flow in an agitated batch with pitched blade multi-stage impellers. Effects of various geometrical parameters (blade number, distance between impellers) of pitched blade multi-stage impellers on pumping ability have been investigated. Axial velocity profiles were measured by LDA (Laser Doppler Anemometry). Axial pumping capacities were obtained by integration of measured axial velocity profiles in outflow from impellers. Main attention was focused on the effect of the distance between impellers in multi-stage configurations, on their pumping capacity and flow in the mixing bath in comparison with an independently operating pitched blade impeller with the same geometry. In case of a relatively close distance between impellers H3/d = 0.5 - 0.75, the multi-stage impeller creates only one circulation loop and the impellers itself behave identically as pumps in series. However for relative higher distance of impellers than H3/d = 1.25, the multi-stage impeller creates two separated circulation loops.

This paper presents a numerical analysis of an agitated fully baffled cylindrical vessel with a down pumping four blade worn or unworn pitched blade impeller (α = 45° and 30°) under a turbulent flow regime. CFD simulations predict the pumping capacity of the system equipped by worn and unworn pitched blade impeller. Experimental data were taken from the authors’ previous work and compared with results of numerical computations. A good agreement with experimental data was obtained. The ensemble-average mean velocity field with worn and unworn impellers was computed. It follows from the simulation results that the wear rate of the impeller blade has a significantly negative effect on the velocity distribution in an agitated liquid. The greater the destruction of the worn blade, the higher is the deformation of the velocity field around the rotating impeller, with a simultaneous decrease in impeller pumping capacity.

A sliding mode controller for the photovoltaic pumping system has been proposed in this paper. This system is composed of a photovoltaic generator supplying a three-phase permanent magnet synchronous motor coupled to a centrifugal pump through a three-phase voltage inverter. The objective of this study is to minimise the number of regulators and apply the sliding mode control by exploiting the specification of the field oriented control scheme (FOC). The first regulator is used to force the photovoltaic generator to operate at the maximum power point, while the second is used to provide the field oriented control to improve the system performance.The whole system is analysed and its mathematical model is done. Matlab is used to validate the performance and robustness of the proposed control strategy.

The aim of this paper is to analyze various CO2 compression processes for post-combustion CO2 capture applications for 900 MW pulverized coal-fired power plant. Different thermodynamically feasible CO2 compression systems will be identified and their energy consumption quantified. A detailed thermodynamic analysis examines methods used to minimize the power penalty to the producer through integrated, low-power compression concepts. The goal of the present research is to reduce this penalty through an analysis of different compression concepts, and a possibility of capturing the heat of compression and converting it to useful energy for use elsewhere in the plant.

Most high-pressure fuel pumps for compression-ignition engines manufactured today are cam driven. These pumps have numerous advantages, such as low energy consumption and limited production costs. However, a problem arising from the nature of the cam mechanism is an unfavorable distribution of forces in the camshaft-plunger-cylinder system of a delivery section. The authors have proposed an innovative pump design that eliminates most of the problems present in conventional solutions. The pump utilizes a gear-based hypocycloid drive. This paper focuses mainly on the strength analysis of the two critical components (countershaft and mount) of the subassembly under the highest load – simulations were carried out for different critical load states. The following procedure of estimating fatigue life was adopted for computations: the operational evolution of stresses will be systematized to the set of amplitude stresses and mean stresses by means of the “Rainflow” method. The results obtained in the work showed that the main factor determining change of stresses was the presence of clearances in the pump mechanism. It has been proved that the values of clearances have a negative influence on the power transmission in particular – their presence results in loads being carried by the countershaft and not by the support inter-operating with it. This may cause frictional wear of teeth, leading to the improper operation of the transmission. The analysis showed that the mount was designed correctly. This facilitates the use of less demanding constructional materials.

The purpose of the work was to experimentally determine the characteristics of the prototype of a Roto-Jet pump (the Pitot tube pump) during its operation under conditions typical for the domestic micro power plant. The low-boiling fluid, sold under the trade name of HFE7100 and characterised by a zero ozone depletion potential (ODP) coefficient, was used as a working medium in the organic Rankine cycle (ORC). An electric thermal oil heater with a maximum power of 2×24 kWe was used as a heat source. The pump of Roto-Jet type was specially designed for the operation with the following rated parameters of the thermodynamic cycle: nominal flow rate of the working fluid 0.17 kg/s, operating pressure 1.2 MPa. The pump was put under load using an expansion valve that simulated the operation of an expansion machine. The article discusses thermodynamic and flow conditions to be met by the pumping engine as well as results of the experimental research. Moreover, the article includes the operational characteristics of the ORC installation and the Roto-Jet pump obtained during the operation with the target working medium – HFE7100. The engineering problems the authors of this article faced when designing and testing the pumping engine prototype are also presented.

The pump performance and occurrence of cavitation directly depends on different operating conditions. To cover a wide range of operation conditions for detecting cavitation in this work, investigations on the effect of various suction valve openings on cavitation in the pump were carried out. In order to analyse various levels of cavitation in different operation conditions, the effect of the decrease in the inlet suction pressure of the centrifugal pump by controlling the inlet suction valve opening was investigated using this experimental setup. Hence, the acoustic and pressure signals under different inlet valve openings and different flow rates, namely, 103, 200, 302 l/min were collected for this purpose. A detailed analysis of the results obtained from the acoustic signal was carried out to predict cavitation in the pump under different operating conditions. Also, the acoustic signal was investigated in time domain through the use of the same statistical features. The FFT technique was used to analyse the acoustic signal in the frequency domain. In addition, in this work an attempt was made to find a relationship between the cavitation and noise characteristics using the acoustic technique for identifying cavitation within a pump.

Cavitation is an essential problem that occurs in all kinds of pumps. This cavitation contributes highly towards the deterioration in the performance of the pump. In industrial applications, it is very vital to detect and decrease the effect of the cavitation in pumps. Using different techniques to analysis and diagnose cavitation leads to increase in the reliability of cavitation detection. The use of various techniques such as vibration and acoustic analyses can provide a more robust detection of cavitation within the pump. In this work therefore, focus is put on detecting and diagnosing the cavitation phenomenon within a centrifugal pump using vibration and acoustic techniques. The results obtained from vibration and acoustic signals in time and frequency domains were analysed in order to achieve better understanding regarding detection of cavitation within a pump. The effect of different operating conditions related to the cavitation was investigated in this work using different statistical features in time domain analysis (TDA). Moreover, Fast Fourier Transform (FFT) technique for frequency domain analysis (FDA) was also applied. Furthermore, the comparison and evaluation system among different techniques to find an adequate technique incorporating for accuracy and to increase the reliability of detection and diagnosing different levels of cavitation within a centrifugal pump were also investigated.