Pneumatic jigging: Influence of operating parameters on separation efficiency of solid waste materials.
This article aims to provide insights into the factors that contribute to the separation efficiency of solid particles. In this study, a pneumatic jigging technique was used to assess the separation of solid waste materials that consisted of copper, glass and rubber insulator. Several initial experiments were carried out to evaluate the strengths and limitations of the technique. It is found that despite some limitations of the technique, all the samples prepared for the experiments were successfully separated. The follow-up experiments were then carried out to further assess the separation of copper wire and rubber insulator. The effects of air flow and pulse rates on the separation process were examined. The data for these follow-up experiments were analysed using a sink float analysis technique. The analysis shows that the air flow rate was very important in determining the separation efficiency. However, the separation efficiency may be influenced by the type of materials used.
Role of water velocity for efficient jigging of iron ore
Abstract Upgrading of iron ore by jigging has been an emerging trend. Typically −10.0 + 0.15 mm material is considered for jigging where the problem of separation of finer particles is inherent. A detailed investigation is carried out to understand the behavior of various size fractions of the feed material during jigging in order to improve the separation efficiency. It has been realized that the separation of particles is mostly influenced during the period when particles are fluidized. Fluidization of particles in jigs depends on the rate of change of water velocity that in turn is controlled by the maximum water velocity attained during the pulsion stroke of the jig cycle. Experimental results at different maximum water velocities show three important relations between the feed characteristic and the maximum water velocity. Firstly, coarser feed needs higher maximum water velocity for better jigging efficiency, secondly, maximum water velocity for a feed must be matched to the largest size of the particles present in the feed, and finally, even at optimal maximum water velocity different size fractions of a feed respond differently and as a result ideal separation is never achieved. These observations reinforce the need for sizing the feed and then optimizing the maximum water velocity for each feed. This study also brings into focus the concept of size ratio which is used to predict the segregation potential of binary particulate systems.
Reconceptualizing Vagrancy and Reconstructing the Vagrant: A Socio-Legal Analysis of Criminal Law Reform in Canada, 1953-1972
This article explores significant reforms to the vagrancy section of the Criminal Code during the mid-to-late twentieth century. By locating the reforms within their unique social, political, and economic climates, I examine how they reconceptualized the offence of vagrancy and concomitantly reconstructed the vagrant as a social problem. The reforms played a seminal role in reducing the number of vagrancy offences, eventually leading to the demise of vagrancy in the criminal law. Yet, while the "vagrant" ceased to exist in the law, the law still continues to preserve vestiges of the vagrant in a highly gendered manner.