| 1. |
- Alatalo, Johanna, et al.
(författare)
-
Influence of pebble mill operating conditions on measurements with an in-mill sensor
- 2011
-
Ingår i: Minerals & metallurgical processing. - 0747-9182. ; 28:4, s. 193-197
-
Tidskriftsartikel (refereegranskat)abstract
- Autogenous grinding is a process of reducing the particle size distribution of an extracted ore by using the ore itself as the grinding media. It is a process that is difficult to control and there is a lack of knowledge of the events occurring inside the mill. To find out more about how the mill behaves under different processing conditions, a full factorial test was performed with iron ore in a pilot-scale pebble mill at the LKAB R&D facility in Malmberget. To complement this work, a strain gauge detector was embedded in one of the mill’s rubber lifters, the Metso Minerals continuous charge measurement (CCM) system, and was used to get more information about the charge dynamics. The data from the experiments has been analyzed. For production purposes, an increase in the number of particles smaller than 45 μm can be regarded as a probable increase in the production rate. The analysis shows that there will be an increase in fines at 65% of critical speed, especially when the mill is 45% full. This setting will also increase the power consumption, but improves the grindability of the ore even more. The deflection of the lifters is smaller for lower critical speeds. A higher degree of filling also gives a smaller toe angle and a higher shoulder angle as expected.
|
|
| 2. |
- Forssberg, Eric, et al.
(författare)
-
Pilot plant trials of new gravity concentration equipment
- 1987
-
Ingår i: Minerals & metallurgical processing. - 0747-9182. ; 4:2, s. 87-89
-
Tidskriftsartikel (refereegranskat)abstract
- In this technical note, pilot-scale tests with two types of gravity concentrators, the Knelson separator and the Mark VIIA Reichert spiral concentrator are described. The experimental work was concentrated on the relatively untried Knelson separator. The materials tested have different concentration characteristics: one was an artificial ore with excellent liberation characteristics and a wide difference in density between valuable and gangue minerals; the others include a spiral concentrate containing gold from the gravity circuit of Boliden, Sweden, an old scheelite tailing from Yxsjoberg, Sweden, and an auriferous ore containing gold that had not been crushed to full liberation. The latter three materials contained other heavy minerals, e. g. pyrite, that can interfere with concentration.
|
|
| 3. |
- Franca, S.C.A., et al.
(författare)
-
Beneficiation of Brazilian diatomite for the filtration application industry
- 2003
-
Ingår i: Minerals & metallurgical processing. - 0747-9182. ; 20:1, s. 42-46
-
Tidskriftsartikel (refereegranskat)abstract
- Laboratory experiments were performed on a Brazilian diatomite from Bahia State to produce an industrial product for use as a filter aid. Bench and pilot-plant tests were conducted. The tests consisted of diatomite desegregation, organic matter and clay removal, filtration, drying and calcination. Calcination temperature and sodium carbonate addition influenced diatomite particle size distribution. Optimum filtration rates for calcined products were obtained at 900°C and 47 minute residence time with 3% (w/w) of sodium carbonate addition. The resultant products met the specifications for filter aids.
|
|
| 4. |
- He, Mingzhao, et al.
(författare)
-
Rheological behaviors in wet ultrafine grinding of limestone
- 2007
-
Ingår i: Minerals & metallurgical processing. - 0747-9182. ; 24:1, s. 19-29
-
Tidskriftsartikel (refereegranskat)abstract
- This paper investigates the effects of solids concentration and the addition of Dispersant S40 on the flowability of original and ground limestone slurries. A rotational viscometer with a concentric cylinder geometry and a controlled-stress rheometer with a cone-and-plate geometry were used to characterize the rheological behaviors of limestone slurries. The rheological behavior of original limestone slurries ( < 100 gm) is transformed through different types of flows with increasing solids concentration. The use of Dispersant S40 can improve the slurry flowability by decreasing viscosity and eliminating Casson yield stress. It is therefore used as a grinding aid for the wet ultrafine grinding of limestone. The rheological behaviors of ground limestone slurries vary with grinding from a starting dilatant flow-ability to a resulting pseudoplastic one with an evident Casson yield stress in combination with a thixotropic character. The appearance of pseudoplastic flowability combining thixotropy is related to the fineness of a ground product and its specific surface area, which are both correlated to solids concentration and the additive amount of Dispersant S40. In addition, the accurate rheological characterization of time-dependent fluids is dependent on the instruments used and operation conditions.
|
|
| 5. |
- Hosseini, S. H., et al.
(författare)
-
Adsorption studies of smithsonite flotation using dodecylamine and oleic acid
- 2006
-
Ingår i: Minerals & metallurgical processing. - 0747-9182. ; 23:2, s. 87-96
-
Tidskriftsartikel (refereegranskat)abstract
- The interaction of various concentrations of sodium sulfide, dodecylamine (DDA) and oleicacid (OA) on smithsonite were investigated at different pH levels using zeta potential, contact angle, microflotation and diffilse-reflectance FT-IR studies. Flotation results show that the recovery and contact angle are enhanced to 94% and 115 degrees, respectively, with a dodecylamine concentration of 1.6 x 10(-3) M and a pH of 11.5. The optimum sodium sulfide consumption was found to be 2.6 x 10(-2) M. Zeta potential measurements showed less negative charge after DDA treatment on the surface of pure crystalline smithsonite. The recovery and contact angle for oleic acid flotation rises to 93% and 105 degrees respectively, with an oleic acid concentration of 1.1 x 10(-3) M and a pH of 10. The zeta potential in the case of using oleic acid showed a more negative charge after oleic acid treatment on the smithsonite surface. The FT-IR spectra studies of smithsonite conditioned with DDA confirmed the adsorption of DDA on the smithsonite surface. The spectra show that the mineral surface is changed partially to a ZnS layer after sodium sulfide treatment. The spectra confirmed the formation of zinc oleate on the smithsonite surface after oleic acid treatment. A comparison of the results using cationic and anionic collectors showed that the different adsorption densities of the reagents in two cases conferred different degrees of hydrophobicity on the smithsonite surface.
|
|
| 6. |
- Ikumapayi, Fatai, et al.
(författare)
-
Recycling process water in sulfide flotation, Part A: Effect of calcium and sulfate on sphalerite recovery
- 2012
-
Ingår i: Minerals & metallurgical processing. - : Springer Science and Business Media LLC. - 0747-9182. ; 29:4, s. 183-191
-
Tidskriftsartikel (refereegranskat)abstract
- In order to predict and minimize detrimental production problems due to the recycling of process water in sulfide ore processing, the influence of major species, calcium and sulfate in process water on sphalerite flotation was investigated through Hallimond tube flotation, zeta potential, diffuse reflectance Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) measurements using sphalerite mineral sample. Assessment of process water species in flotation was done using deionized water, process water and simulated water containing calcium and sulfate ions in experiments. Hallimond flotation shows increased sphalerite floatability in process water compared to deionized water, but no significant effect on the presence of calcium and sulfate ions in deionized water using isobutyl xanthate as a collector. The presence of calcium ions reduced the sphalerite's negative zeta potential, while at higher concentrations, a charge reversal occurred, at about pH 11. FTIR and XPS studies revealed the presence of surface-oxidized sulfoxy and carbonate species on sphalerite at pH 11.5 in deionized water, process water and water containing calcium and sulfate ions. These surface species do not influence xanthate adsorption.
|
|
| 7. |
- Ikumapayi, Fatai, et al.
(författare)
-
Recycling process water in sulfide flotation, Part B: Effect of H2O2 and process water components on sphalerite flotation from complex sulfide
- 2012
-
Ingår i: Minerals & metallurgical processing. - : Springer Science and Business Media LLC. - 0747-9182. ; 29:4, s. 192-198
-
Tidskriftsartikel (refereegranskat)abstract
- Hydrogen peroxide production was measured during the grinding of a complex sulfide ore, and its oxidizing effect on solid surfaces was investigated using Fourier transform infrared spectroscopy (FTIR) with diffuse reflectance attachment measurement. In turn, an attempt was made to correlate the formation of hydrogen peroxide, surface oxidation and sphalerite flotation. Additionally, in order to predict and minimize detrimental production problems due to the recycling of process water in sulfide ore processing, the effects of major components of calcium and sulfate species present in recycled process water and the effect of temperature on sphalerite flotation were investigated through bench-scale flotation tests using complex sulfide ores. The significance of process water species in flotation was studied using tap water, process water and simulated water containing calcium and sulfate ions. Formation of hydrogen peroxide was revealed during the grinding of the complex sulfide ore, and its formation was counteracted by diethylenetriamine (DETA). The FTIR spectrum of the pulp solid fraction showed varying degrees of oxidized surface species, which are related to the concentration of H2O2 analyzed in pulp liquid. Bench-scale flotation using two different complex sulfide ores showed that sphalerite recovery is better in process water than in tap water. Flotation results also indicated a varied recovery of sphalerite at different temperatures in either tap water or process water.
|
|
| 8. |
- Javadi, Alireza, et al.
(författare)
-
Formation of hydrogen peroxide by chalcopyrite and its influence on flotation
- 2013
-
Ingår i: Minerals & metallurgical processing. - 0747-9182. ; 30:4, s. 212-219
-
Tidskriftsartikel (refereegranskat)abstract
- Formation of hydrogen peroxide (H2O2), an oxidizing agent stronger than oxygen, by chalcopyrite (CuFeS2), which is a copper iron sulfide mineral, during grinding, was investigated. It was observed that chalcopyrite generated H2O2 in pulp liquid during wet grinding and also the solids when placed in water immediately after dry grinding. The generation of H2O2 in either wet or dry grinding was thought to be due to a reaction between chalcopyrite and water where the mineral surface is catalytically active in producing •OH free radicals by breaking down the water molecule. Effect of pH in grinding medium or water pH in which solids are added immediately after dry grinding showed lower the pH value more was the H2O2 generation. When chalcopyrite and pyrite are mixed in different proportions, the formation of H2O2 was seen to increase with increasing pyrite fraction in the mixed composition. The results of H2O2 formation in pulp liquid of chalcopyrite and together with pyrite at different experimental conditions have been explained by Eh-pH diagrams of these minerals. This study highlights the necessity of revisiting the electrochemical and/or galvanic interaction mechanisms between the chalcopyrite and pyrite in terms of their flotation behaviour.
|
|
| 9. |
- Jonsén, Pär, et al.
(författare)
-
Validation of tumbling mill charge induced torque as predicted by simulations
- 2013
-
Ingår i: Minerals & metallurgical processing. - : Springer Science and Business Media LLC. - 0747-9182. ; 30:4, s. 220-225
-
Tidskriftsartikel (refereegranskat)abstract
- Understanding mill charge motion is important. In the charge, the center of gravity is shifted from the rotational center of the mill system, and its motion is induced by rotation of the mill, while at the same time the charge creates a torque into the mill system. Breakage of ore particles and wear of liners/ball media are closely linked to this motion. To study these phenomena in a physically correct manner, numerical models for different parts of the mill system are needed. Validations of such models are scarce, because of the difficulty to measure inside a tumbling mill.Experimental measurements in a lab mill were done for a number of load cases: varying feed material, mill filling, mill speed and pulp liquid. The mill is set up to measure the charge-induced torque. The accuracy is good with relative uncertainty smaller than ±2% for relevant load cases.A full three dimensional numerical model of the whole mill is used to predict induced torque. Agreement between predicted and measured torque at steady-state is good. In addition, the model can accurately predict the mill start-up behavior for torque and mill power. This proves that the model is physically correct, and can be used for modeling large-scale mills.
|
|
| 10. |
- Larsson, Sofia, et al.
(författare)
-
Simulation of the flow field in an iron ore pelletizing kiln
- 2016
-
Ingår i: Minerals & metallurgical processing. - : Springer Science and Business Media LLC. - 0747-9182. ; 33:3, s. 144-148
-
Tidskriftsartikel (refereegranskat)abstract
- The flow field in a rotary kiln, used in an iron ore pelletizing process, was investigated using a three-dimensional computational fluid dynamics model. The model is isothermal, downscaled and simplified. The objective was to examine the possibility of capturing the unsteady motion of the flame seen in the real kiln. The results from the simulations were compared with recorded images of the real process. The results demonstrate the possibility of quickly getting an overview of the flow field in the kiln. The main, unsteady behavior of the flame was captured. The model may be used as a tool in the ongoing work of improving and optimizing the pelletizing process.
|
|
