High concentration thickened tailings slurries that appear to be homogeneous mixtures often contain coarse particles that settle in the pipeline under laminar flow conditions. During pipeline transport, these coarse particles may eventually settle to the pipe invert. Frequently, these high concentration suspensions are misclassified as homogeneous slurries, leading to the use of incorrect models for predicting the pressure gradient and flow behaviour. This paper discusses the use of a non-Newtonian two-layer model to predict the pressure gradient of a high concentration suspension with a sliding bed in laminar flow conditions. The success of the model is measured by comparing the results obtained by applying the model to experimental results for a typical iron ore tailings slurry. It was found that the model predicted the laminar flow pressure gradient with less than 10% error for slurries with carrier fluid yield stresses above 10 Pa.
In the present study, laboratory experiments were performed to investigate the geotechnical properties of four different tailings, including two iron tailings (coarse and fine) and two copper tailings (coarse and fine).
The mining industry is becoming more and more attracted to dry stacking as a method of mine tailings management. The development of bigger-sized plates now allows metal producers to utilize pressure filtration technology to process flow rates of up to 200,000 tonnes per day of dry solids, which was undreamed of just a few years ago. The advantages of this technology include very low cake moisture content, significant savings in water usage and the possibility to recover product (when required) without the need of CCD washers. The filter press technology combined with bigger-sized plates enables filters to be installed in remote sites with high average rainfalls, offering the mining company the possibility of a safer and more sustainable environmental impact, thanks to a stable stack of solid material that requires less room than traditional thickened residue dams. The aim of this presentation is to show the latest studies where this technology has been applied.
?This study aims to analyses the use of high-pressure filter presses in the dewatering of slurry resulting from mineral processing, especially iron ore mining tailings and slimes. The current practice problems of deposition of fines in tailing dams were analyzed, as well as the new challenges faced by the sector in relation to water scarcity and energy efficiency. Are listed technological differentials implemented in Matec filter presses and analyzed the benefits in application of this technology, such as higher water recovery, reduce of environmental impacts and reduce of operating costs for handling and disposal of waste. Lastly, we analyze the filtration tests performed on iron ore tailings and slimes and a case study.
High availability of filtration equipment is essential for reducing the capital cost on tailings filtration projects. At the same time, low operational costs are needed to maintain mine profitability. High availability, greater than 90%, and low operational costs can be achieved at the same time through good equipment design, good building layout, automation, and proper maintenance procedures.
Cemented paste backfill (CPB) has become known as a superior secondary ground support technique and mine tailings storage method for stoping. Extensive scientific research has been conducted by the authors on CPB to provide the Red Lake operation (RLO) of Evolution Mining with an optimised backfill placement process. Due to these complex factors and interactions, a rational CPB material design process was assessed to demonstrate the safety aspects related to a continuous pour. For this purpose, an extensive field monitoring program was required to quantify the CPB performance and characteristics. There are two different ways of optimising the CPB design to maximise placement rate: (i) optimising the type and amount of binder added to the system, and (ii) optimising the CPB placement process underground. Optimisation of binder type and dosage is relatively easy as the required backfill stand-up strength is based on block dimensions, stope stability, and extraction sequencing. Four stopes were instrumented with total earth pressure cells (TEPCs) and piezometers to capture the pressures acting on the fill fence structures and the strengthening response of the CPB plug within the stopes. This paper summarises the results of each of the tests performed. Based on the results obtained from this study, it was concluded that RLO can safely conduct continuous CPB pours with appropriate safeguards and protocols in place. It is important to note that this paper is a summary of the CPB performance and characteristics in RLO longhole stopes and does not reflect site-specific safety procedures, protocols, and critical controls required for a more aggressive pouring regime.
This paper investigates the work carried out by DeGrussa Mine and the Weir Technical Centre (WTC) of Weir Minerals Australia, in developing a process to produce a consistent cemented paste backfill that is fully sheared and presents the lowest possible yield stress and pressure gradients during the underground transport phase. The existing twin shaft paste mixer on DeGrussa Mine was not providing sufficient shear or time of shear to deliver a fully homogenised product. The project to improve the paste backfill rheology involved quantifying the performance of the twin shaft mixer as well as the required rheological parameters of yield stress and pressure gradient of the paste backfill product. In order to achieve the required outcome, a centrifugal pump was installed after the mixer to provide the shear energy required to produce a fully sheared paste backfill rapidly and continuously. A fully sheared consistent paste backfill is required to ensure predictable transport of the paste backfill throughout the DeGrussa Mine reticulation system. This predictability of paste backfill performance results in a safe and robust reticulation system, together with ensuring pipeline integrity. The lower pressure gradients, manifest by the fully sheared paste backfill, also allow DeGrussa Mine to fill stopes that are at a distance that would otherwise require a positive displacement pumped system.
The paper will present a new pulsation reduction system (PRS) invented by MHWirth. This PRS is in contrast to conventional pulsation damperssuitable to eliminate high-frequency pulsation of reciprocating diaphragm pumps. Brief description of functionality: The new damper is connected to the propelling fluid chamber of the diaphragms. The propelling fluid, a hydraulic oil, is used as a damping medium, converting the pulsation energy described above into heat by throttle effects. This effect is similar to a shock absorber. The paper will also explain the PRS effects, present operational data from field application and address the following benefits by using it in a tailings and storage facility:
The most commonly used dewatering technologies for the filtration of tailings from ore processing are pressure filters, filter presses, belt filters and rotary vacuum disc filters. The vacuum disc filter type in around 80% of all applications is the most economical of these technologies in terms of capital and operating cost, especially when modern high performance disc filters are used. The Boozer disc filter is a big diameter high performance vacuum disc filter that has set the pattern in a multitude of applications including the alumina industry and in dewatering coal slurries. In the past decade, this type of disc filter has established itself in applications of tailings dewatering, such as tailings from gold/copper, zinc and gold/silver mines. The reasons for its successful operation in tailings dewatering are: (a) high throughput and dewatering performance, (b) operational reliability even in the case of varying feed conditions, (c) simple and robust design, (d) ease of maintenance, (e) a small footprint. To achieve higher solids throughput rates, or to achieve the lowest possible filter cake moisture, HiBar filtration and HiBar steam pressure filtration offer new solutions in tailings dewatering. HiBar filtration and the HiBar steam pressure filtration are advanced continuous pressure filtration processes realised on rotary disc filters that are installed in a pressure vessel. The application of hyperbaric pressure of up to 6 bar (instead of a vacuum) ensures a high filtration rate and dewatering capability even with filter cakes of fine particles where high cake resistance and capillary forces in the cake must be overcome. With HiBar steam pressure filtration, the use of steam under special conditions improves demoisturing to the furthest extent, leading to the lowest values of moisture content. The drier HiBar filter cake improves the cake handling and disposal with steeper dumping slopes, resulting in reduced disposal area and improved safety of the disposal site.
?Several large copper mines are evaluating improvements in the tailings dewatering circuits. Most prevalent alternatives being considered optimize their thickening technologies or the implementation of tailings filtration and stacking. This requirement to optimize water recovery is due to a variety of factors; the deficit and high cost of the water make-up, environmental restrictions, and community relationships. The recent failures in conventional tailing deposit structures and the potential change to reduce the footprint of tailings impounds may also drive the desire to consider alternate technologies. This paper presents technical and economic review of alternate technologies, considering capital investment and operational costs. The five (5) selected alternatives include thickening technologies, pressure filters and a combination with cyclones for classification and filtration of the coarser fraction and thickening of the finer fraction. The selected alternatives are developed and evaluated at trade off study level.