Mathematical and empirical description of screen blocking

Abstract

This paper addresses the process of sieve holes blocking taking place while screening fine-particulate materials and provides an analytical description of the phenomenon. Empirical tests performed as part of this research provided dependences specifying the parameters of sieve holes blocking that could be applied in practice. The process of sieve holes blocking is unfavourable and inevitable. It is related with the screen clearance coefficient which is one of the fundamental characteristics of all screens. The grains whose dimensions are similar to the dimensions of the sieve holes block those holes, causing their exclusion from the active surface area of the screen. This phenomenon results in diminished performance and efficiency of the screening process. Screening is a very common industrial practice, and various designs of screens and types of sieves are available. That is why the subject of this paper is so important. The screen blocking coefficient is the measure of sieve holes blocking. In order to describe the process of screen blocking, a mathematical model is presented and a method for determining the screen blocking coefficient is proposed. Furthermore, the authors list the factors that have a significant influence on the degree of sieve holes blocking, i.e. the shape of the screened material, the toss indicator and the content of hard-to-screen grains in the feed. This paper is the first one to have thoroughly described the issue of screen blocking. B Lawinska Katarzyna

Dynamic Modeling of a Vibrating Screen Considering the Ore Inertia and Force of the Ore over the Screen Calculated with Discrete Element Method

“…e literature presents several models and studies covering different aspects of vibrating screens. Models of screens using a probabilistic approach [12,13], stratification and passage in the screening process [14], particle movement [15][16][17][18][19], screen blocking [20], finite elements [5,[21][22][23][24], crushing plants [7,25], and phenomenological models [26] can be found in the literature. Dynamic models of vibrating screens can simulate motion of the vibrating screen structure and show good agreement with experimental measurements [27] and finite element method (FEM) results [22].…”

Development and test of a Lunar Excavation and Size Separation System (LES3) for the LUVMI‐X rover platform

“…For more detailed discussions of the relation between F I G U R E 5 Details of the cam profiles required for actuation of the spring-loaded gates (with roller bearings [m]) for both fine (j; top left) and coarse fraction (i; top right). The bottom images show both cam profiles with a fully engaged follower amplitude, frequency, and passing probability (see Katarzyna et al, 2016;Kudrolli, 2004;Lawinska & Modrzewski, 2017;Li & Tong, 2015).…”

“…In the present experiments, vibrations with a large acceleration and low frequency were applied (see Section 4.1, for details), as this vibration mode was able to provide the necessary agitation of particles to allow for an efficient separation given the provided mass of analogue material. For more detailed discussions of the relation between amplitude, frequency, and passing probability (see Katarzyna et al, 2016; Kudrolli, 2004; Lawinska & Modrzewski, 2017; Li & Tong, 2015).…”

Production of Agglomerates, Composite Materials, and Seed Coatings from Tannery Waste as New Methods for Its Management

“…This paper describes the use of unit processes in methods of processing waste generated by the leather industry on the basis of chromium tanning shavings and waste collagen preparations for the purpose of their reuse. The granulometric composition of shavings was determined on the basis of screen analysis [46,47], taking into account sieve hole blocking [48][49][50][51]. Zingg's classification was used for analyzing the shavings shape (using a KAMIKA Instruments analyzer, Warsa, Poland).…”