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- Alemrajabi, Mahmood, 1989-, et al.
(författare)
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Isolation of rare earth element phosphate precipitate in the nitrophosphate process for manufacturing of fertilizer
- 2016
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Ingår i: IMPC 2016 - 28th International Mineral Processing Congress. - : Canadian Institute of Mining, Metallurgy and Petroleum. - 9781926872292
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Konferensbidrag (refereegranskat)abstract
- In the present study, the recovery of rare earth elements (REE) in the nitrophosphate process of fertilizer production is investigated. The apatite has been recovered from iron ore tailings by flotation. After digestion of apatite in concentrated nitric acid, Ca(NO3)2.4H2O is first separated by cooling crystallization and then the REEs are recovered by precipitation. Optimum conditions in these steps have been determined in a previous study. The precipitate mainly consists of CaHPO4.2H2O and REE phosphates. In the present study, selective dissolution and re-precipitation have been studied in order to obtain a precipitate that is more concentrated in REEs. The precipitate was selectively dissolved in nitric and phosphoric acid at different acidities (pH 6 to 0) with the liquid /solid ratio of 100 mL/g. It is shown that most of the CaHPO4.2H2O and other calcium containing compounds will be dissolved at pH 2 while the REE phosphates are not dissolved above a pH of approximately 2. Thus, by partial dissolution of the REE precipitate at pH 2.5 most of the solid calcium phosphates will be dissolved and the remaining solid phase, which is more concentrated in REEs, can be filtered off as a fairly concentrated REE solid mass and the liquor can be recycled back to recover more P nutrients. Alternatively, the REE enriched precipitate was dissolved completely in nitric acid and re-precipitated again by addition of ammonium hydroxide to pH 1.2. A chemical equilibrium software, MEDUSA (Puigdomenech, 2013) has been used to evaluate the experimental results and to estimate the optimum conditions for selectively dissolving the precipitate.
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| 2. |
- Hedvall, Per, et al.
(författare)
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The industrial way to make product cost calculations in crushing & screening
- 2016
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Ingår i: IMPC 2016 - 28th International Mineral Processing Congress. - 9781926872292 ; 2016-September
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Konferensbidrag (refereegranskat)abstract
- The main objective of this study is to introduce the new Sandvik’s production cost-model within Crushing & Screening (C&S) technology. So far, there have been different ways of determining different production costs in the industry, however, the previously published and presented methods have not been very efficient in calculating the costs per product and metric ton. Accordingly, the current study has been planned and started in collaboration with Lund University to provide an accurate and easy to implement cost estimation program to determine the costs for crushing and screening plants worldwide. The proposed model has been adapted to fit the C&S processes of different rocks/ores fractions. The result is presented as cost per ton of the end product(s). Within this paper the cost estimation results for 3 different crushing and screening plants are presented based on the information obtained from the following sources: a) documents at Sandvik SRP, b) Sandvik’s crushing & screening internal/external machines/plants data and information, c) literature studies, including the use of Sandvik’s internal/external simulation and software programs, d), visiting the crushing and screening plants,e) interviews, information systems’ data, and, f) testing and observations by ourselves. In order to improve the level of accuracy and the validity of the attained results, simplistic Monte-Carlo simulations have been used, where needed. The achieved results, so far, have proven the reliability of the model. The calculated cost estimations have shown an accuracy over 80% when they compared with real cost data obtained from plant practices. The current cost calculation model, will offer the possibility of: o Calculating the production costs in proposed and/or existing C&S plant. o Making detailed cost analyses for the end product(s) in proposed and/or existing C&S plants. o Determining the profitability of each finished product when it’s required. o Cost optimization by potentially cutting the cost for part of C&S plant with an existing plant practice.
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| 3. |
- Lishchuk, Viktor, 1984-, et al.
(författare)
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Evaluation of sampling in geometallurgical programs through synthetic deposit model
- 2016
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Ingår i: (IMPC 2016). - : Canadian Institute of Mining, Metallurgy and Petroleum. - 9781926872292
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Konferensbidrag (refereegranskat)abstract
- The main purpose of geometallurgy is to develop a model to predict the variability in the mineralprocessing performance within the ore body. Geometallurgical tests used for developing such a model need to be fast, practical and inexpensive and include as an input data relevant and measureable geological parameters like elemental grades, mineral grades and grain size. Important in each geometallurgical program is to define the number of samples needed to be sent for geometallurgical testing to enable reliable metallurgical forecast. This is, however, a complicated question that does not have a generic answer.To study the question on sampling a simulation environment was built including a synthetic orebody and sampling & assaying module. A synthetic Kiruna type iron oxide - apatite deposit was established based on case studies of Malmberget ore. The synthetic ore body includes alike variability in rock types, modal mineralogy, chemical composition, density and mineral textures as its real life counterpart. The synthetic ore body was virtually sampled with different sampling densities for a Davis tube testing, a geometallurgical test characterising response in magnetic separation. Based on the test results a forecast for the processing of the whole ore body was created. The forecasted parameters included concentrate tonnages, iron recovery and concentrate quality in terms of iron, phosphorous and silica contents.The study shows that the number of samples required for forecasting different geometallurgicalparameters varies. Reliable estimates on iron recovery and concentrate mass pull can be made with about 5-10 representative samples by geometallurgical ore type. However, when the concentrate quality in terms of impurities needs to be forecasted, the sample number is more than 20 times higher. This is due to variation in mineral liberation and shows the importance of developing techniques to collect qualitative information on mineral and ore textures in geometallurgy.
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| 4. |
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| 5. |
- Quist, Johannes, 1985, et al.
(författare)
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Investigation of Roller Pressure and Shear Stress in the HPGR Using DEM
- 2016
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Ingår i: XXVIII International Mineral Processing Congress Proceedings. - 9781926872292 ; 2016-September:Canadian Institute of Mining, Metallurgy and Petro
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Konferensbidrag (refereegranskat)abstract
- HPGRs have since introduced in the 1980s (Kellerwessel, 1993; Schönert, 1988), now becomeintegral comminution units at several minerals processing plants around the world. Even though a lot of theinitial issues concerning performance, availability and wear have been addressed and solved there are stillphenomena and aspects which can be improved and understood further. Schönert and Sander (2002)presented experimental results and a mechanistic model including the internal force dynamics between therollers and the compacted bed. They derived expressions for the pressure distribution involving most of theinfluencing terms and effects. However, in order to solve the differential equations several of the termsvanish by assumptions. The Schönert and Sander model reflects the experimental data in many aspects butthe predicted shear force distinctly deviates from the experimental results at the angular position of thepeak pressure level. This finding suggests that the particle to particle interaction and breakage process inthe different zones seen in Figure 1 are complex and difficult to model using analytical models. Anumerical modelling approach using DEM does not require the same amount of assumptions andsimplifications of boundary conditions. Hence such modelling may provide further knowledge and vitalunderstanding. In this paper the breakage process is simulated in order to investigate the shear slipbehaviour and how it relates to different operating variables. A laboratory scale HPGR corresponding tothe experimental setup used by Schönert (2002) have been modelled in EDEM (DEM-Solutions). Thebonded particle model (BPM) is used for modelling quartz particles (Potyondy, 2004). The breakage modelstrength parameters are calibrated against interparticle breakage experiments in an Instron 400RDcompression device. The contact model parameters are calibrated using calibration methods developed byQuist (2015). The floating roller dynamics are modelled using a spring-damper system. Results presentinsights regarding the interparticle slip behaviour as well as the frictional tangential force distribution onthe rollers. The simulated roller pressure distribution shows good correspondence with previously reportedfindings in the literature.
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