The Feasibility of Reclaiming Shell Material from Investment Casting

This report examines the feasibility of investment shell component reclamation. Shell material components and their compositions are investigated with an industry survey, a study of the available literature, and analysis of specimen shell materials. physical properties and factors related to the reclamation and reuse of shell materials are described. Well known mineral processing methods are capable of producing concentrates of the various shell components. The theory and techniques of some applicable processes are discussed to assist with the development of reclamation operations. The recommended methods are; comminution by roll crushing, component concentration by screening, gravity settling or heavy medium separation. Aluminosilicate stucco (a major component of many investment shells) can be recovered in a form suitable for reuse as backup stucco. Zircon (a minor component in many shell compositions) -can be concentrated in an impure form, and subsequent caustic liberation treatments can remove the intermixed silica phases. Reuse of such zircon in investment casting may be possible but will require careful qualification testing. Fused and crystalline silica (major components of most shell compositions) are not reusable for investment casting. The feasibility of reclamation will be influenced by individual foundry choices of materials, composition and shell practice.HWRIC Project No. RRT-10NTIS PB92-16219

Waste Management Study of Foundries Major Waste Streams: Phase I

Research on emission control and waste disposal is the number one priority within AFS. In an industry survey conducted by AFS, ten top areas of concern were outlined, headed by sand system waste and emissions from molding, pouring, melting and shakeout in iron and steel green sand foundries. The objective of the present program is to define the foundry waste streams and emissions, establish where the streams originate, and their make-up. Currently available technology will then be identified to minimize, treat, dispose, or reuse the waste. Information obtained will be summarized into a manual for use by foundry operators. Additional research and development needed to respond to environmental regulations will be identified. A primary driving force for this work is the Clean Air Act Amendments of 1990 which will set new regulations for air emissions from foundries for 189 hazardous air pollutants (HAP) by 1997. This report covers the first year's research on the nature of the foundry waste streams in the form of air emissions from processes of coremaking, molding, pouring, and shakeout and establishes where they originate, and their makeup. Binder chemicals are a major potential contributor to emissions from coremaking and subsequent processes. Remaining objectives will be accomplished in a further development of the program. The approach used includes a review of all available information. Sources were the technical literature, suppliers of chemicals to foundries, AFS workshops, USEPA Office of Air Quality Planning and Standards, technical meetings, and visits to foundries. The data in the literature on organic HAP relate to workplace health and safety data which identify chemical types and concentrations, and emissions during pouring and cooling. There are no significant variations of temperature, metal composition, and metal to sand ratio to allow extrapolation to different systems. It is apparent that additional research is needed to determine the important parameters that control HAP emissions. Information from suppliers and other sources was combined with data from the literature to identify 16 HAP non-metal chemicals potentially present in air emissions from foundries. In addition, HAP from specific binder systems are also defined. The next phase of this program will identify currently available technology to minimize, treat, dispose, or reuse the waste. Information obtained will be summarized into a manual for use by foundry operators.HWRIC Project RRT-1