1997 TMS Annual Meeting: Thursday Abstracts

UPDATE OF THE PRACTICE OF COPPER ELECTROREFINERY BLEED-OFF TREATMENT

Session Chairpersons: N.L. Piret, Piret & Stolberg Partners, Im Licht 12, D-47279 Duisburg, Germany; Ivan M. Santos Moraes, Caraiba Metals, Dias D'Avila, Bahia, Brazil

8:30 am INVITED

ASPECTS OF IMPURITIES CONTROL AT CARAIBA METALS ELECTROREFINERY: Jose Luiz Rodrigues Bravo, Caralba Metais S.A.(CMSA), Via do Cobre N° 3700, A.l.O. - Copec, Dias D'Avila - Bahia - Brazil

The production of electrolytic copper with assured quality corresponding to international standards in a conventional electrorefinery of a custom smelter, is a hard and cautious task, if no advanced technologies for selective control of electrolyte impurities are available. The improper control of the amount of As, Sb and Bi in the anode that enter de tankhouse, attributable either to a bad schedule of concentrate input or to the unavailability of clean concentrates from the international market, as well as the lack of means to maintain the suitable level of these elements in the electrolyte together with other operational circumstances, can result in off-grade copper, as well as affect the starting sheet quality chemically and physically. This paper presents in a practical way the relationship between the operational conditions and the cathode and starting sheet quality produced at CMSA, covering the period of the last five years of operation, discusses the technologies available in the market for antimony and bismuth removal and compares the results of testwork, achieved in the laboratories of CMSA, using two resins not associated with patented technologies.

9:00 am

REMOVAL OF ANTIMONY AND BISMUTH FROM COPPER ELECTROLYTE DEVELOPMENT OF A COMMERCIAL PLANT AT AMARILLO COPPER REFINERY: R.M. Cunningham, Asarco Inc, Amarillo, TX; J.V. Calara & M.K. King, Asarco Technical Services Center, Salt Lake City, UT

Asarco operates one of the largest individual copper electrorefineries in the world at Amarillo, Texas. The feed is a mixture of anodes from Asarco smelters and copper purchased from various primary and secondary sources. The variation in feed makes it imperative that the refinery practices state-of-the-art quality control to minimize the effects of unwanted impurities. In late 1993, a plant designed to significantly reduce the antimony and bismuth levels in the electrolyte was commissioned. The purification plant uses ion exchange technology in conjunction with a novel stripping system developed by Zeneca Specialties, which permits the recycling of the eluant. Thereby, the extremely high costs of stripping with conventional reagents are avoided. In addition, the environmental impact of treating the eluant for recovery of antimony and bismuth is minimized. This paper outlines the development of the technology and, in particular, describes the operational practices and improvements at Amarillo since the commissioning of the plant.

9:30 am INVITED

BLEED-OFF TREATMENT OF HK-SECONDARY COPPER ELECTROREFINERY: Dr. R.F. Dobner, Huttenwerke Kayser AG, Posffach 1560, D44505 Lunen

After a short introduction of the electrolysis process at HK and explanations concerning the anodes used, the regulation and buffering of bleed will be described and the principles of technology for processing of bleed will be presented. Modernization aspects, especially installation equipment, and the different types of evaporators used will be described in detail. Besides experience made with acid-resistant materials - stainless steel, enamel, plastics - will be reported. Environmental aspects such as water and air pollution will be outlined briefly and in conclusion the quality of products obtained as well as quality control will be presented.

10:00 am BREAK

10:20 am INVITED

PROCESS OPTIONS IN THE TREATMENT OF COPPER REFINERY ELECTROLYTE BLEED: James E. Hoffmann, Jan H. Reimers & Associates USA Co., P.O. Box 420545, Houston, TX

This paper will briefly review the conventional technologies employed for the treatment of copper refinery electrolyte bleed. The distinction between decopperizing and electrolyte purification will be emphasized. The strengths and weaknesses of conventional practice will be reviewed and a number of process options to address the weaknesses of present process technology will be described and evaluated. The effect of process selection upon energy consumption and the environmental aspects of process effluent control will be discussed.

10:50 am

IMPROVING THE QUALITY OF THE NICKEL SULFATE HEXAHYDRATE PRODUCED AT CARAIBA BY APPLYING THE QUALITY FUNCTION DEPLOYMENT METHOD (Q.F.D.): Ivan Marcelo Santos Moraes and Group of Q.F.D., Caraiba Metais S.A., Via do Cobre N° 3700, A.l.O. - Copec, Dias D'Avila - Bahia Brazil, CEP 42800-000

Caraiba Metais has a plant for the purification and the crystallization of the crude nickel sulfate removed from its copper electrolyte purification system. In November 1994, an interdepartmental group was formed to study the Q.F.D method, through its application on the improvement of the quality of the nickel sulfate hexahydrate. The team, formed with representatives of the following areas: production, technology, marketing, sales, maintenance, laboratory and TQC office, had also the task of checking the applicability of the method to other products of the company. This paper describes the main steps such as the survey of customer's demands, the preparation of the quality matrix, the planned and the designed quality and the consequent identification of the engineering bottlenecks. It is also shown how these bottlenecks were studied and solved. The application of the method allowed the team to identify means of increasing the production capacity by 40%, to improve the intrinsic quality of the product (including packaging), and to increase the reliability of the process.

11:20 am

COPPER SULFATE RECOVERY USING FLUIDIZED BED CRYSTALLIZATION: Martin Schranz, Robert J. Farrell, Swenson Process Equipment Inc., 15700 Lathrop Ave., Harvey, IL 60426

Copper sulfate pentahydrate is recovered from the spent etchant waste stream of a printed circuit/wiring board manufacturing facility. The fluidized bed crystallizer contains submerged cooling surfaces (through which a coolant is passed) which are bathed in a stream of air. The air bubbles provide agitation which improve heat transfer, reduce fouling and maintain crystals in suspension. The recently patented fluidized bed crystallization apparatus (US 5,523,064) has significant advantages when compared to a conventional surface cooled crystallizer including capital cost, ease of operation and production of larger more uniform crystals.