Investigation Of Local Clays As Alternative Furnace Lining Materials

ABSTRACT

This work investigates local clays as alternative furnace lining materials. The suitability of some local clays as alternative to materials was investigated. The clay samples were first analysed to determine their chemical compositions. Fireclay bricks test specimens were prepared by standard method. They were then tested for properties such as apparent porosity, bulk density, thermal shock resistance, fired shrinkage, refractoriness and cold crushing strength. The result obtained showed that both test samples qualify as high melting fireclays. The refractory properties measured revealed them as being usable as refractory bricks when blended.

CHAPTER ONE

1.0                                                      INTRODUCTION

1.1                                        BACKGROUND OF THE STUDY

Clay in addition to silica sand is one of the principal moulding material used for all type of casting irrespective of whether the casting is ferrous or non-ferrous (Atanda et al,2012). Clay is very useful and plays very crucial roles in the industrial development of any nation. Clay is useful in foundry applications and varies in grain shape, grain composition, relative surface, grain size, and grain distribution patterns. These properties, in addition to chemical analysis, sinter point, and expansion characteristics play an important part in the choice of clay used as a binder for moulding or core aggregate in metal casting. Clay is defined as those particles of sand (under 20 microns in diameter) that fail to settle at a rate of 25mm per minute, when suspended in water (American Foundry Society –AFS, 2005). Clay imparts the necessary bonding strength to the moulding sand so that after ramming, the moulding does not lose its shape. The higher the quantity of the clay the lower the permeability of the moulding sand.

Nigeria is endowed with a lot of clay deposits, but only few deposits are utilized for foundry application. The low utilization of clay deposits in Nigeria may be as a result of lack of adequate information about their existence and suitability for foundry application. Due to insufficient information on the foundry properties of sand and clay deposit in Nigeria, foundry raw materials such as silica sand, clay binders and additives that are used for producing effective casting via sand casting by foundry industries in Nigeria are sometimes sourced from overseas.

Refractory materials are inorganic materials which can withstand high temperatures (usually above 1500^OC) under the physical and chemical action of molten metal, slag and gases in the furnace.

The raw materials for the production of various refractory products include kaolinite (Al₂O₃.2SiO₂.2H₂O), chromite (FeOCr₂O₃), magnesite (MgCO₃) and various types of clays. Other additives such as sawdust and binders are also available locally. Alumino silicate and magnesite refractory products are the major types of refractories used in Nigerian manufacturing industries. Though metallurgical industries are the major consumers of refractory products, other demands come from chemical, glass, boiler and petrochemical industries. The refractory needs of these industries were well over 300,000 tonnes as at the year 2000 (Omowumi 2001).

In this work, various properties of two local clays were investigated to determine their suitability for producing refractory bricks for furnace lining.

1.2                                               PROBLEM STATEMENT

Refractory products are required for various processes in chemical, ceramic, petrochemical, oil, foundry and iron and steel industries. Unfortunately there is no refractory industry in Nigeria despite the fact that there are abundant deposits of clay and other raw materials needed for the production of refractory products. Despite having extensive clay mineral deposits in Nigeria, Nigeria continues to depend on the importation of refractory materials for many of her industries. Nigeria imported about 27 million metric tonnes of refractory materials in 1987 (Obadinma, 2003).and this led to high cost of Refractory materials. In other to solve the unavailability and high cost of Refractory materials, local clays are use as an alternative.

1.3                                  AIM AND OBJECTIVE OF THE STUDY

The main aim of this work is to investigate the use of local clays suitability for producing refractory bricks for furnace lining.

1. To investigate the process involved in using local clays as refractory materials.
2. To determine the suitability for using clay for furnace lining

1.4                                             PURPOSE OF THE STUDY

The purpose of this study is to eliminate the scarcity and high cost of Refractory materials by using local clays.

1.5                                                SCOPE OF THE STUDY

Clay is useful in foundry application. It is one of the principal moulding materials used for all type of casting whether ferrous or non-ferrous. The scope of this work covers an investigation of the suitability of clay as a lining material for refractory application. This was done by investigating the physio- chemical properties of the clay. The physio-chemical properties of the clay were determined by physical and chemical analysis. X- Ray Fluorescence (XRF) spectroscopy technique was used to determine the chemical composition of the clay.

1.6                                               LIMITATION OF STUDY

As we all know that no human effort to achieve a set of goals goes without difficulties, certain constraints were encountered in the course of carrying out this project and they are as follows:-

1. Difficulty in information collection: I found it too difficult in laying hands of useful information regarding local clays and this cause me to visit different libraries and internet for solution.
2. Financial Constraint: Insufficient fund tends to impede the efficiency of the researcher in sourcing for the relevant materials, literature or information and in the process of data collection (internet).

• Time Constraint: The researcher will simultaneously engage in this study with other academic work. This consequently will cut down on the time devoted for the research work.

1.7                                     PROJECT ORGANISATION

The work is organized as follows: chapter one discuses the introductory part of the work,   chapter two presents the literature review of the study,  chapter three describes the methods applied, chapter four discusses the results of the work, chapter five summarizes the research outcomes and the recommendations.