The filtering of sandy tailings from the reverse cationic flotation processes and the subsequent stacking of these tailings has shown to be a very strong trend in Brazilian iron ore mining, especially after accidents involving geotechnical structures known as tailings dams, but also due to concern of mining companies to develop a disposal technique that is more complacent with the environment and the surrounding society. In order to develop the sandy tailings filtration project, a fundamental requirement was the correct choice of filtration technology among the many existing ones. For the material object of this study, the filter with vertical discs presented itself as the most productive due to factors such as granulometry, specific surface of the material and the humidity required in the filtration product. Several exploratory and material characterization tests were carried out for this purpose. Disc filters have the principle of operation linked to the difference in atmospheric pressure and the vacuum pressure induced by pumps. The vacuum must act on the filtering screens next to the filter heads and, in order not to drop the yield, the system must be sealed hydraulically. As previously mentioned, there are basically two ways to hydraulic seal the system. The first and most common in Brazilian iron ore filtration is carried out through barometric columns and the other is using filtrate pumps installed directly in the vacuum receiver of the filtration facilities. The decision of which method to use has major implications for the design of the filtering installation and the comparison between the two conditions mentioned is the objective of the present work.
?Hindustan Zincs Rampura Agucha Mine is a world class orebody that has successfully transitioned from an open pit operation to an underground sublevel open stoping with paste backfill operation. The mine currently has two identical paste plants that each can produce between 160-185 m3/hr of cemented paste backfill. Plant #1 was commissioned in 2014 and plant #2 was commissioned in 2019. The two plants are equipped with Putzmeister piston pumps that pump from the plant to the edge of the pit, down a borehole to the North and South main ramps and then down the ramps to the top of the underground orebody approximately 500 m below surface. Each plant was designed with an operating and standby paste pump. Most of the orebody can be reached from these main lines, however, at the extreme north end of the pit, there is portion of the underground orebody that is above the uppermost underground delivery level and at a significant horizontal distance from the main paste trunk lines. Because of the location of these northern stopes, an overland pipeline to the north of the pit is required before entering a borehole down to the stoping levels. This lateral distance on surface and underground would have resulted in very high pressure on the paste pumps, and a decision was made to temporarily install the standby pump from plant 2 at a booster station that would allow the northern stopes to be reached with a 2 stage pumping system instead of a single stage pumping system. The booster station was installed and commissioned in 2019 and this paper discusses the design principles regarding booster stations in general as well as the specific design, commissioning, and operational experiences with the booster station at Rampura Agucha Mine.
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:
?There is an increasing trend in iron ore mining in Brazil regarding the disposal and treatment of sandy tailings from concentration processes by reverse cationic flotation techniques. Filtering and later disposal of sandy tailings in piles known as PDR (Tailings Disposal Pile) has been shown to be a rising method to the detriment of known tailings dams. In the case study in question, the tailings thickening operation is too far from the filtration and stacking point, so it was necessary to consider a material transport mode between the two operations (Thickening and Filtration), which was the tailings pipeline. The pipeline is 6.7 km long tail and 52.0 m static lift designed to operate with process variations especially in terms of percent solids and variations in the beneficiation plant rate. The drive consists of five centrifugal pumps with 600 HP motors and the piping follows the ANSI B36.10 dimensional standard and the API 5L Grade B material standard with 16 inch diameter. To support the pipeline sizing a fundamental step was to perform the characterization of the material to be transported. Several tests were performed of granulometry, rheology, abrasiveness, solids density, slurry corrosivity, inclination angle of the pipeline, among others. The results of the tests were used to calibrate the mathematical models. The pipeline was evaluated considering the steady-state and transient flow regime. The results of the steady-state analysis made it possible to specify the quantity and model of the pumps, as well as to evaluate the velocities and pressure losses. The transient analysis, however, was performed to identify the operating scenarios that lead to the highest pressures and thus confirm the characteristics of the pipelines and consider the necessary hydraulic protections.