Experimental study the impact forces of tumbling mills

2016 ◽  
Vol 231 (2) ◽  
pp. 283-293 ◽  
Author(s):  
MM Soleymani ◽  
M Fooladi Mahani ◽  
M Rezaeizadeh
Keyword(s):  
Experimental Study ◽  
Critical Speed ◽  
Operating Parameters ◽  
Solid Concentration ◽  
Copper Ore ◽  
Slurry Concentration ◽  
Impact Forces ◽  
Tumbling Mills ◽  
Mill Speed ◽  
The Impact

Impact forces are one of the mechanisms for grinding in mill. This takes place when the particles elevated by the lifters get into cascade motion and their fall on the load causes the breakage of other particles. The present paper aimed to study the impact forces in terms of variables like: mill speed, solid charge filling (ball filling), slurry concentration, and slurry filling. In this work, the influence of these operating parameters was investigated using a pilot mill. To this end, a copper ore was used to prepare slurry at different solid concentration. The tests covered a range of slurry filling from 0 to 2 with five different balls filling between 12% and 36% of mill volume and six different speeds between 60% and 85% of critical speed. The results delineate that the increase in the mill speed leads to a remarkable increase in the amount and frequency of the impact forces. Increasing the charge volume leads to decrease the maximum impact forces. The results show that with the increase in slurry filling and the resulting formation of a pool, the impact forces will decrease. Moreover, it is found that with the increase in slurry concentration, the slurry will act as a damper decreasing the impact forces.

Experimental investigation of the power draw of tumbling mills in wet grinding

2016 ◽  
Vol 230 (15) ◽  
pp. 2709-2719 ◽  
Author(s):  
Moslem M Soleymani ◽  
Majid Fooladi ◽  
Masood Rezaeizadeh
Keyword(s):  
Critical Speed ◽  
Empirical Equation ◽  
Design Criterion ◽  
Copper Ore ◽  
Slurry Concentration ◽  
Critical Design ◽  
Power Increase ◽  
Power Draw ◽  
Tumbling Mills ◽  
Mill Speed

In comminution, mill power plays a major role from the economics standpoint and is a critical design criterion. It is influenced by a range of parameters such as media charge level (ball filling), slurry filling, slurry concentration and mill speed. In this work, the effects of these operating parameters were investigated using a pilot mill (1000 × 500 mm). To this end, a copper ore (−1000 µm) was used to prepare the slurry. The tests covered a range of slurry filling (U) from 0 to 1.7 with media charge between 12% and 36% of the mill volume and six different speeds between 60% and 85% of critical speed. A power analyser was utilized to measure mill power. Increase in mill speed and ball filling leads to a remarkable increase in the amount of the power. Preliminary results show that there is a definite trend between the power and the slurry filling U. Mill power draw is maximum at slurry concentration 60–70% and slurry filling 0.84. An empirical equation was given that fits the data reasonably well.

scholarly journals Experimental Study of Operational Parameters on Product Size Distribution of Tumbling Mill

2020 ◽  
Author(s):  
moslem mohammadi soleymani
Keyword(s):  
Size Distribution ◽  
Critical Speed ◽  
Operational Parameters ◽  
Copper Ore ◽  
Mill Product ◽  
Slurry Concentration ◽  
Pilot Model ◽  
Grinding Media ◽  
Grinding Mechanism ◽  
Mill Speed

Abstract To assess the effects of the mill operating parameters such as mill speed, ball filling, slurry concentration and slurry filling on grinding process and size distribution of mill product, it was endeavored to build a pilot model with smaller size than the mill. For this aim, a pilot mill with 1m × 0.5m was implemented. There are 15 lifters with 50mm height and face angle of 30˚. In the present work, the combination of the balls (40% of the balls with 60mm diameter, 40% of the balls with 40mm diameter and 20% of the balls with 25mm diameter) was used as grinding media with 10%, 15%, 20% and 25% of the total volume of the mill. The experiments were carried out at 60%, 70%, 80% and 90% of the critical speed. The feed of the mill is copper ore with the size smaller than 25.4 mm, which d80 and d50 of them are 12.7 and 8 mm, respectively and slurries with 40%, 50%, 60%, 70% and 80% of solid and the slurry filling between 0.5 and 2.5. The results showed that the best grinding and grading occurs at 70-80% of the critical speed and ball filling of 20-25%. Optimized grinding was observed when the slurry volume is 1-1.5 times of the ball bed voidage volume and the slurry concentration is between 60% and 70%. The mill grinding mechanism in this work is a combination of both impact and abrasion mechanisms.

scholarly journals Experimental Study of Operational Parameters on Product Size Distribution of Tumbling Mill

2021 ◽  
pp. 095440892110627
Author(s):  
Moslem Mohammadi Soleymani
Keyword(s):  
Size Distribution ◽  
Critical Speed ◽  
Operational Parameters ◽  
Copper Ore ◽  
Mill Product ◽  
Slurry Concentration ◽  
Pilot Model ◽  
Grinding Media ◽  
Grinding Mechanism ◽  
Mill Speed

To assess the effects of the mill operating parameters such as mill speed, ball filling, slurry concentration and slurry filling on grinding process and size distribution of mill product, it was endeavored to build a pilot model with smaller size than the mill. For this aim, a pilot mill with 1 m × 0.5 m was implemented. There are 15 lifters with 50 mm height and face angle of 30˚. In the present work, the combination of the balls (40% of the balls with 60 mm diameter, 40% of the balls with 40 mm diameter and 20% of the balls with 25 mm diameter) was used as grinding media with 10%, 15%, 20% and 25% of the total volume of the mill. The experiments were carried out at 60%, 70%, 80% and 90% of the critical speed. The feed of the mill is copper ore with the size smaller than 25.4 mm, which d80 and d50 of them are 12.7 and 8 mm, respectively and slurries with 40%, 50%, 60%, 70% and 80% of solid and the slurry filling between 0.5 and 2.5. The results showed that the best grinding and grading occurs at 70–80% of the critical speed and ball filling of 20–25%. Optimized grinding was observed when the slurry volume is 1–1.5 times of the ball bed voidage volume and the slurry concentration is between 60% and 70%. The mill grinding mechanism in this work is a combination of both impact and abrasion mechanisms.

Experimental Study of Air Gap Response and Wave Impact Forces of a Semi-Submersible Drilling Unit

2006 ◽  
Author(s):  
Saeid Kazemi ◽  
Atilla Incecik
Keyword(s):  
Experimental Study ◽  
Offshore Structures ◽  
Model Tests ◽  
Air Gap ◽  
Scale Model ◽  
Offshore Structure ◽  
The Caspian Sea ◽  
Wave Impact ◽  
Impact Forces ◽  
The Impact

An experimental study for predicting the air gap and potential deck impact of a floating offshore structure is the main topic of this research. Numerical modeling for air gap prediction is particularly complicated in the case of floating offshore structures because of their large volume, and the resulting effects of wave diffraction and radiation. Therefore, for new floating platforms, the model tests are often performed as part of their design process. This paper summarizes physical model tests conducted on a semi-submersible model, representing a 1-to-100 scale model of a GVA4000 class, “IRAN-ALBORZ”, the largest semi-submersible platform in the Caspian Sea, under construction in North of Iran, to evaluate the platform’s air gap at different locations of its deck and also measure the impact forces in case of having negative air gap. The model was tested in regular waves in the wave tank of Newcastle University. The paper discusses the experimental setup, test conditions, and the resulting measurements of the air gap and the wave impact forces by using eight wave probes and three load cells located at different points of the lower deck of the platform.

Experimental study of thermohydraulic characteristics and irreversibility analysis of novel axial corrugated tube with spring tape inserts

2020 ◽  
Vol 92 (3) ◽  
pp. 30901
Author(s):  
Suvanjan Bhattacharyya ◽  
Debraj Sarkar ◽  
Ulavathi Shettar Mahabaleshwar ◽  
Manoj K. Soni ◽  
M. Mohanraj
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Thermal Performance ◽  
Working Fluid ◽  
The Novel ◽  
Heat Exchanger Tube ◽  
Heat Transfer Augmentation ◽  
Corrugated Tube ◽  
The Impact ◽  
Exchanger Tube

The current study experimentally investigates the heat transfer augmentation on the novel axial corrugated heat exchanger tube in which the spring tape is introduced. Air (Pr = 0.707) is used as a working fluid. In order to augment the thermohydraulic performance, a corrugated tube with inserts is offered. The experimental study is further extended by varying the important parameters like spring ratio (y = 1.5, 2.0, 2.5) and Reynolds number (Re = 10 000–52 000). The angular pitch between the two neighboring corrugations and the angle of the corrugation is kept constant through the experiments at β = 1200 and α = 600 respectively, while two different corrugations heights (h) are analyzed. While increasing the corrugation height and decreasing the spring ratio, the impact of the swirling effect improves the thermal performance of the system. The maximum thermal performance is obtained when the corrugation height is h = 0.2 and spring ratio y = 1.5. Eventually, correlations for predicting friction factor (f) and Nusselt number (Nu) are developed.

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