Search

A considerable portion of energy consumption and, as a consequence, operational costs in mineral processing, is associated with comminution. High Pressure Grinding Rolls (HPGR) are appealing for their energy efficiency and resulting lower operating costs. This article evaluates this technology as an alternative to the conventional fused alumina comminution route of a specific plant comprising a complex roll crushing circuit. Two fused alumina samples, called BT and TB, were submitted to HPGR (open circuit) and physical characterization (DWT, BBWI, bulk density, specific gravity) tests. In addition, simulations were conducted using JKSimMet® 6.0 software, aiming to predict the performance of a closed circuit equipment and scale-up of an industrialscale unit. Product size distributions of the open circuit HPGR tests and closed circuit HPGR simulations were compared with the product size distribution required by the industrial comminution circuit. The required throughput was also evaluated. Results show that the alternative HPGR route provides a remarkable potential for circuit simplification, while considerably reducing the number of comminution equipments from 13 to 1, which facilitates operational control and possibly reduces operating costs. [ABSTRACT FROM AUTHOR]

Vertical Shaft Impact (VSI) crushers have been used as interesting alternatives to cone crushers, particularly in the production of aggregates for the construction industry, not only due to their good energy efficiency but also to their ability to generate more isometric and tougher particles, which is highly desirable in cement mortars and concrete applications. Several mathematical models for the VSI crusher have been proposed in the last two decades or so. The Whiten crusher model, originally developed for cone crushers, has served as the basis of several approaches to model VSI crushers. In the present work, the Andersen/Awachie/Whiten model has been used as the basis for modeling a VSI crusher operating in an industrial plant in Brazil, processing quarry rock to product manufactured sand. Nineteen industrial experiments, covering a range of feed rates, rotor speeds, feed distributor types and feed size distributions, have been carried out. The approach demonstrated to be capable of providing satisfactory estimates of the VSI performance, being able to predict the product size distribution and the specific energy consumption with confidence over a wide range of operating conditions. Since it uses a model that is already available in commercial plant simulators, it may be used, with additional expressions, in simulating any desired circuit. Model parameters such as K 3 and T 10 were found to be particularly influenced by key operational variables such as feed rate and rotor frequency. The significant effect of feed rate on the performance of the VSI crusher studied has been discussed on the basis of simulations of the material flow pattern inside its feed distributing system, simulated using the discrete element method. According to these simulations, it has been inferred that change in the behavior of VSI from lower to higher feed rates may be related to the transition from material being fed predominantly to the rotor, to the increasing contribution of the cascading effect. [ABSTRACT FROM AUTHOR]

Comminution is an essential step in processing itabirite ores, given the need to liberate silica and other contaminants from the iron minerals for downstream concentration and then pellet feed production. In general, these ores in Brazil are not particularly hard to crush and grind, but both capital (CAPEx) and operating (OPEx) expenditures in this stage of preparation can be critical for the project, in particular due to uncertainties in iron ore prices. Several circuits have been designed and are in operation for this type of ore in Brazil; however, it is not yet clear which technologies are more cost-effective and in which configuration they should be applied. This work critically analyzes four comminution circuits for an undisclosed case study. For these circuits, CAPEx, OPEx, and some environmental sustainability indices, as well as qualitative technical criteria, were used in the comparisons. This work concludes that two of these process routes, especially those based on more energy-efficient technologies (and one of these still rarely explored even at bench-scale), have demonstrated to be very attractive from multiple standpoints. [ABSTRACT FROM AUTHOR]