An industrial ball mill operating in closedcircuit with hydrocyclones was studied by five sampling surveys. The aim of the present study was to optimise operating parameters ( charge volume, makeup ball size regime, slurry mean residence time, number of hydrocyclones in operation and hydrocyclone's feed solids content (Sf)) with respect to increasing throughout from 225 to 300 tons per ...
Zvith all material staying in the mill for the same residence time T_ However, ball mills have a residence time distribution (RTD) because forward and backward mixing occurs along the mill axis. The model must therefore be extended to allots for the actual RTD, as first described by Reid [14]_ If a fraction (t) dt of the feed stays in the mill ...
For a ball mill with an internal diameter smaller than m, the volumebased residence time threshold is set at 2 min; and for a ball mill larger than m in diameter, the threshold is set at ...
An industrial ball mill was then laser scanned and surveyed, including measurements of residence time distribution. Simulations using the discrete element method were then conducted and the model was applied to simulate closedcircuit operation, resulting in good agreement between measured and predicted size distributions and circulating load ...
Ball mills 1, 2 and 3 from two SAG lines were tested to estimate the residence time distributions by radioactive tracer experiments. Figure 1 presents a schematic of the SAG lines 1 and 2. Each line involves 11 m × m SAG mills.
The ball mill slakers are much more expensive than paste or slurry slakers. They are available in sizes ranging from 1000lb/hr to 50 tons/hr. Figure 3 shows an attritor type vertical ball mill lime slaker. The ball mill slakers are equipped with an external classifier, which separates slurry from the oversized grit and impurities. The oversize ...
A review is made of the methods and theory of measurements of residence time distributions (RTD's) in mills. Literature data on RTD's is assembled. The mean residence times indicate that some industrial mills are operated in the overfilled condition, leading to poor breakage conditions. Although all RTD's are somewhat similar on a ...
Determination of ball mill residence time distributions from tracer data taken in closedcircuit operation. Powder Technology (1982) Gupta et al. The influence of pulp composition and feed rate on holdup weight and mean residence time of solids in a grate discharge ball mill grinding.
The determination of mean residence time is a powerful method for studying the holdup in a cement mill, and hence whether the mill is operating in the required steel to clinker ratio. To determine the mean residence time accurately it is necessary to correct for the recycle of tracer, and a method of correction is given. ... Rod and ball mills ...
Fresh feed and separator grits were combined and fed to the mill. The ball mill has an inside diameter (inside liners) of m. Its length can be varied by combining different tube shells with a length of 25 or 50 cm in the range of m. Fig. 3 shows the mill. The material, which is discharged pneumatically by the mill ventilation ...
Highlights The dispersion properties in a continuous ball mill are analyzed theoretically. The Peclet number determines the residence time distribution. Trends derived from the theory are within agreement with data reported. Mill length and diameter are predicted to affect greatly the Peclet number. A proportional relation for the Peclet number is valid regardless of mill sizes.
Grinding Studies. Two kinds of mills, BBM and LBM, were used to achieve the desired P 80 passing percentage of 150 μm with an acceptable range of hematite liberation (> 75%) at optimum grinding time. The BBM is a standard ball mill having a length and diameter of 300 mm × 300 mm with smooth liner as shown in Fig. rotating drum is attached to a gearbox and has adjustable speed knob.
Cho et al. (2011) studied the effect of operating variables on the mean residence time and RTD of solids in a centrifugal mill. RTD were measured by means of an aluminium powder tracer. A model based on one large and two small fully mixed reactors was fitted to the RTD data, where the mixing regime was described by a single parameter due to a ...
Radioactive tracer results are given for a number of particulate unit processes with special emphasis on wetdischarge ball mills. This study is concerned with the derivation and application of the finitestage transport concept for modeling residence time distributions (RTD's) originally proposed by Adler and Hovorka (1961). This sixparameter ...
Hassanzadeh, A. Measurement and modeling of residence time distribution of overflow ball mill in continuous closed circuit. Geosyst. Eng. 2017, 20, 251260. [Google Scholar] Mori, Y.; Jimbo, G.; Yamazaki, M. On the residence time distribution and mixing characteristics of powders in opencircuit ball mill. Kagaku Kogaku 1964, 28, 204213.
This is due to the lower residence time per pass. In a properly designed circuit, each finely ground particle of the required product size has ample opportunity to exit the grinding circuit after each pass through the mill. As a result, few 10 micron fines are generated in the grinding circuit.
Abstract. Experimental investigations concerning the residence time distributions of both the solid and the liquid phase have been carried out for a continuously operated stirred ball mill. It is admissible to consider the suspension as a singlephase fluid. Residence time distributions are found to be well described by an axial dispersion model.
Keywords: residence time distribution; closedcircuit ball mills; parametric RTD estimation; constrained leastsquares estimation; industrial tracer tests 1. Introduction Ball mills are widely used in mineral processing due to their flexibility and versatility in reducing the particle size at the level required in the concentration stages [1 ...
Request PDF | On Dec 1, 2013, François K. Mulenga and others published Introduction to the use of the attainable region method in determining the optimal residence time of a ball mill | Find ...
From the simulation results, it was found that the ball mill would produce 300 +75 micron particles efficiently from a feed of size less than mm at a rate of 75 tph. In terms of residence ...
That is, holdups affect the residence time distributions [16] and the grinding rates [7,8], both of which determine the size distributions of ground product. Holdups were measured in various ball mills, sometimes as one of important factors controlling the residence time distributions.
© DZCrusher - كل الحقوق محفوظة
