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.
Recovery of metal from slag/mixed metal generated in ferroalloy plants—a case study
Abstract Most ferroalloy plants lose considerable amounts of metal in their slag and metal–slag mix. A potential source of income for alloy smelters is the massive reserves of metal contained in their slag dumps. Depending on the smelting process and the age of the slag dump, the metal contents vary between 3% and 15%. One important means of reducing costs has been the widespread introduction of metal-from-slag recovery techniques in vogue since mid-1990s. Recovery of metal from mixed metal and slag through mechanized means is widely practiced and assumes immense importance from the metal recovery and environment point of view. A metal-from-slag plant allows producers to cope with fluctuating ferroalloy markets. During times of low prices, a producer can shut down furnaces and rely on the low-cost metal-from-slag product to remain viable. When demand is high, the plant is a low-cost means to boost production. Simple physical (gravity) separation methods like jigging and tabling are in vogue for the recovery of metal. Virtually all charge chrome plants now use the crushing/jigging process to recover chrome alloy from both stockpiled and currently produced slag. Studies were carried out at R&D, Tata Steel to develop a flow sheet for the recovery of metal from metal–slag mix generated in its charge chrome (ferrochrome with 50–60% chromium) plant, Bamnipal. The studies showed that in the case of the charge chrome plant, crushing of mixed metal and slag to below 10 mm followed by jigging of the −10+1 mm material and tabling of the −1 mm material would help recover 10 tpd of metal from the 18 tpd of mixed metal. Based on the studies, a plant is now operational at the Ferro-Alloy Plant (FAP), Bamnipal which recovers ferrochrome metal from mixed metal and slag.
The Illinois Legislature
It further provides that the county must have voted "for license" at the last general election on that subject. Also, that the petition, together with all names and addresses on it, must first be published in at least two issues of some newspaper published in the town where the petition was circulated, for at least ten days before the petition is acted upon. Any officer authorized to issue licenses violating the provisions of this act is liable to a fine of from $500 to $1000 and imprisonment in the county jail for from two to twelve months. The act does not repeal any local laws forbidding the sale of liquor, but is cumulative to all anti-liquor laws now in force. The final section is: "This Act being necessary for the public peace, health, and safety, shall take effect and be in force from and after December 31, 1913." The postponement of the time for going into effect was made io order not to interfere with licenses already issued and to give the liquor dealers time to adjust themselves to the provisions of the act. But the liquor people denied that the emergency clause could be attached to an act the operation of which was postponed nearly a year. They called attention to the omission of the word "immediate," and declared that the postponement was in itself sufficient evidence that it was not necessary for the "immmediate preservation of the public health, peace and safety." A petition for reference was circulated and the necessary number of signatures was secured. The attorney-general was first asked for his opinion as to whether the act was subject to the referendum. That officer stated that he could find no precedent for such a case. Basing his decision on reason and common sense he declared the act not subject to the referendum. The circuit court was then asked for a write of mandamus against the secretary of state to compel him to submit the act, but the court refused to grant it, saying that the attachment of the emergency clause was evidence that the legislature intended to prevent its submission. At this writing the question is pending on appeal before the supreme court.