IJCBS, 1(2012):85-90 Ademoh, 2012 Bentonite clay as a composite mix with grades 1 and 2 Nigerian acacia species for binding foundry sand moulds Nuhu A. Ademoh Department of Mechanical Engineering, Federal uUniversity of Technology, P. M. B 65, Minna, Nigeria Abstract The potential of composite combination of each of grades 1 and 2 Nigerian acacia species exudates and bentonite clay as sand mould binder was investigated. The study involved foundry property analyses of sand mould specimens bonded with composites mixes of grades 1 and 2 acacia species exudates and bentonite clay. Standard foundry equipment that included universal strength machine, permeability meter, hardness tester, shatter index machine and quick moisture teller in the foundry workshop and laboratory of Ajaokuta Steel Company Limited, Nigeria were used as the research equipment. The foundry properties measured were the moisture content, green and dry compressive strength, permeability and shatter index of sand moulds bonded with varied combinations of the composite materials. The result was compared to existing foundry standard and past related work. It showed that composite combination of 8% grade 1 acacia species with 1% bentonite clay was a suitable binder for green and dry sand mould for casting light steel, grey iron and non-ferrous alloys. A composite of 8% grade 2 acacia species and 1% bentonite clay was a suitable binder for green and dry sand mould for casting grey iron and non-ferrous alloy. Presence of bentonite clay generally improved mould sand binding ability of grades 1 and 2 Nigerian acacia species exudates. Key words: Acacia exudates, bentonite clay, foundry, binder. Full length article Received: 15-10-2011 Revised: 19-12-2011 Accepted: 04-01-2012 Available online: 15-01-2012 *Corresponding Author, e-mail: nuhuadam@yahoo.com 1. Introduction Acacia species exudate is a natural resin that contains arabin; a semi solidified sticky fluid oozing from incision made on bark of trees called acacia species [1]. The four commercial grades of acacia species produced in Nigeria include grade 1 (acacia Senegal), grade 2 (acacia Seyal), grade 3 (combretum) and grade 4 (neutral) [2]. Nigeria is second largest of the material in the world with an average annual production output of 20,000 tonnes since 2005. Sudan is the world biggest producer and exporter (http://www.nigeriaembassychina.com). Fennema [3] described it as a compound mixture of arabino galactan, oligosaccharide, polysaccharide and glycoprotein; less consistent than other hydrocolloids. Ademoh and Abdullahi [4] found grade 1 acacia exudates mixed with 2-3% moisture suitable mainly for non-ferrous, malleable and grey iron castings. Plain grade 2 acacia species was found suitable for non-ferrous casting at compositions that range from 4.5% to 13% [5]. Bentonite clay is of American origin and is used in moulding sand as colloidal clay binding agent [6]. Its deposits exist in most acacia species producer countries like Nigeria making it easily available [7-8]. Bentonite clay has long been an established foundry sand binder but acacia exudates are only used as additives to core binders because of its high cost [9]. This study aims at blending organic resins like acacia exudates with traditional mineral binder like bentonite clay to give high quality synthetic composite sand binder that is very suitable for selected use in the sub-sector. The objectives are to separately blend different compositions by weight of each of grades 1 and 2 Nigerian acacia species with varied quantities of bentonite clay as composite binder for sand; analyze them for properties like green and dry compressive strength; permeability and hardness; shatter index and moisture content and compare result to standard in Table 1 [10] to ascertain its efficacy. The significance of the research lies in the fact that foundries can shift from more expensive and hazardous chemical binders to these composites that of high purity, cheaper and non corrosive materials for better savings on process costs and risks. 2. Materials and methods Properties of mould sand bonded with composites made of each of grades 1 and 2 Nigerian acacia species exudates with bentonite clay were measured using standard test specimen and equipment in laboratory of the Ajaokuta Steel Company Limited in Nigeria. The moisture content; green and dry compressive strength, hardness, permeability and shatter index which are the properties reported by as the most important in ascertaining suitability of sand and the active binder for foundry use. They were adopted in this International Journal of Chemical and Biochemical Sciences Journal Home page: www.iscientific.org/Journal.html © International Scientific Organization