AREMU OPEYEMI SIWES REPORT PDF

KWARA STATE UNIVERSITY, MALETE The University for Community Development FACULTY OF PURE AND APPLIED SCIENCES A REPORT STUDENTS’ INDUSTRIAL WORK EXPERIENCE SCHEME (SIWES) CARRIED OUT AT DANGOTE SUGAR REFINERY. BY STUDENT’S NAME: AR...

KWARA STATE UNIVERSITY, MALETE The University for Community Development FACULTY OF PURE AND APPLIED SCIENCES A REPORT STUDENTS’ INDUSTRIAL WORK EXPERIENCE SCHEME (SIWES) CARRIED OUT AT DANGOTE SUGAR REFINERY. BY STUDENT’S NAME: AREMU OPEYEMI SAMUEL (MATRIC NUMBER): 21/57BC/001 OCTOBER, 2024. 1  A REPORT STUDENTS’ INDUSTRIAL WORK EXPERIENCE SCHEME (SIWES) CARRIED OUT AT DANGOTE SUGAR REFINERY BY STUDENT’S NAME: AREMU OPEYEMI SAMUEL (MATRIC NUMBER): 21/57BC/001 A SIWES REPORT SUBMITTED TO THE DEPARTMENT BIOCHEMISTRY, FACULTY OF PURE AND APPLIED SCIENCE, KWARA STATE UNIVERSITY, MALETE IN PARTIAL FULFILMENT OF THE REQUREMENTS FOR THE AWARD OF BACHELOR OF SCIENCE [B.Sc. DEGREE IN BIOCHEMISTRY] OCTOBER, 2024. 2  DECLARATION I hereby declare that this report of Students’ Industrial Work Experience Scheme (SIWES) carried out at “DANGOTE SUGAR REFINERY, shed 20 NPA Wharf Port Complex, Lagos” is my report and has not been submitted by other person for any degree or qualification at higher institution. I also declare that the information provided therein are mine and those that are not mine are properly acknowledged. ………………………………....…………………………… Name of Student Signature and date 3  CERTIFICATION This is to certify that this report was written by Aremu opeyemi samuel(21/57bc/001) of the Department of Biochemistry, Faculty of Pure and Applied Sciences, Kwara State University, Malete. The report has been read and approved as meeting part of the requirement for the award of Bachelor of Science (B.Sc. Hons) Degree in Biochemistry of Kwara State University, Malete. ………………………….. ……………………….. Dr. M.A. Alabi Date (Departmental SIWES Coordinator) ………………………….. ……………………….. Dr. R.A Aladodo Date (Departmental Coordinator) 4  DEDICATION This report is dedicated to my wonderful guardians, Mr. Akinwunmi and Mrs. Atosu Esther Akande, whose unwavering support, guidance, and encouragement have been my foundation. Their constant belief in my potential has fueled my journey and inspired me to strive for excellence. I am forever grateful for their wisdom, patience, and love, which have been a beacon of strength through every challenge. This work is a reflection of their faith in me, and I dedicate it to them with heartfelt gratitude and respect. 5  ACKNOWLEDGEMENT I would first give thanks to Almighty God, who gave me the gift of life, and made everything possible. This acknowledgement would be incomplete if I fail to express my gratitude to my lovely family most especially my guardians, Mr. and Mrs. Akande, for their parental and financial support to my success. My appreciation also goes to All the staffs of Dangote sugar refinery for all their impartation of knowledge made towards my Industrial Training program. 6  REPORT OVERWIEW The Student Industrial Work Experience Scheme established by the Federal Government of Nigeria was aimed at exposing student of higher institution to acquire industrial skill and practical experience in their approved course of study and also to prepare students for the industrial work situation which they are likely to meet after graduation. This technical report is based on the experiences gained during my six months of Industrial Training at Dangote sugar refinery, Shed 20 wharf, Apapa,Lagos. This report provides an in-depth look into the essential processes of sugar refining and highlights the key quality tests performed to ensure product consistency and purity. The process begins with affination, where raw sugar crystals are washed to remove surface impurities. This is followed by clarification, where methods like carbonatation and phosphatation are applied to neutralize and remove further non- sugar substances from the solution. Next, filtration removes any remaining solids, improving syrup clarity in preparation for decolorization. During decolorization, the syrup is treated with activated carbon or ion-exchange resins to eliminate residual colorants, producing a bright, clear solution. The syrup then undergoes evaporation and crystallization, where it is boiled to remove water and initiate sugar crystal formation. Centrifugation then separates the crystals from the syrup, with washing to remove residual syrup. In the final stages, the sugar is dried and cooled to prevent clumping, followed by screening to achieve uniform crystal size before packaging. Quality control tests are conducted throughout the process, monitoring sucrose content, pH levels, impurities, 7 turbidity, ash content, moisture, and microbial safety to ensure a high-quality refined sugar product. I was opportuned to work in several sections which were the  Vhp  Talo-clarification  IER  PAN Boiling  Centrifugal station  Dryer and rotex  Vitamin A  Bagging  Labouratoty[main and special Lab]  Water treatment  Boiler house. Most importantly, it describes the activities and my experience gained during the period of the training, it also stated the problems encountered and also gave suggestion for improvement of the scheme. 8  TABLE OF CONTENTS TITLE PAGE DECLARATION CERTIFICATION………………………………………………………………… i DEDICATION……………………………………………………………………...ii ACKNOWLEDGEMENTS….…………………………………………………… iii REPORT OVERVIEW.………………………………………………………iv LIST OF TABLES LIST OF FIGURES CHAPTER ONE: INTRODUCTION 1.1 Meaning and relevance of SIWES 1.1.1 Evolution of SIWES 1.1.2 Background of SIWES 1.2 Aim and objectives of SIWES CHAPTER TWO; THE ESTABLISHMENT 2.1 Description of Dangote sugar Refinery 2.1.1 location and brief history of DANGOTE SUGAR REFINERY 2.2 Objectives of DANGOTE SUGAR REFINERY 2.2.1 Vision and mission statement of DANGOTE SUGAR REFINERY 2.2.2 Organogram of Dangote Sugar Refinery 2.2.3 Overview of Dangote Sugar Refinery’s Refining Process CHAPTER THREE: DEPARTMENTS/SECTIONS IN DANGOTE SUGAR REFINERY 3.1.1 Process 3.1.2 Engineering 3.1.3 Administrative 3.1.4 Finance department 9 3.1.5 Quality assurance 3.1.6Materials department 3.2Detailed explanation of the Process Department CHAPTER FOUR: EQUIPMENTS USED AND THEIR FUNCTIONS 4.1 Equipment and their function CHAPTER FIVE: 5.1 Summary 5.2 Challenges Encountered 5.3 Recommendations 5.4 Solution proffered REFERENCES: 10 CHAPTER ONE: INTRODUCTION 1.1. Meaning and Relevance of SIWES The Student Industrial Work Experience Scheme (SIWES) is a program established by Industrial Training Fund (ITF) in 1973 to solve the problem of lack of adequate practical skills needed for employment in industries by Nigerian graduates of tertiary or higher institutions. It was designed with the aim of exposing undergraduates to the situations they will face after graduation; it is an expectation on the institutions of higher learning to produce graduates that satisfies employer’s requirements both in theoretical and practical aspects. The importance of SIWES cannot be over emphasized, as it is appropriate for diversifying learning amongst Nigerian students. 1.1.1 Evolution of SIWES The student Industrial Work Experience Scheme (SIWES) was introduced into the curriculum of Nigeria’s higher institutions in 1974 as one of the mainstream programs to be carried out by the Industrial Training Fund. Before this period, the I.T.F. was only involved in training manpower for commerce and industry as well as other establishments that need training for manpower development in the nation. Owing to the drive for Industrialization, the Military Head of State, General Yakubu 11  Gowon established SIWES, to be undergone by students from Universities, Polytechnics and Colleges. 1.1.2 Background of SIWES In the earlier stage of Science and Technology education in Nigeria, students were graduating from their respective Nigeria institution without any technical knowledge or work experience. It was in this view that students undergoing science and technology courses where mandated for students in different institution in the view of widening their horizons so as to enable them have technical knowledge or working experience before graduation. The student industrial work experience scheme (SIWES) is the acceptable skill training program, which forms part of the approved minimum academic standard in the various degree programs for all the Nigerian Universities. It is an effort to bridge the gap between theory and practice of engineering and Technology, science, agriculture, medical, Management and other professional educational programs in Nigeria Tertiary institutions. It is aimed at exposal to machines and equipment, professional work areas and workers in industries and other organizations. The minimum duration of the program is directed by the industrial Training Fund (I.T.F) and the National Universities Commission (N.U.C). The scheme is a tripartite program involving the students, Universities and industries (employers of labor). It is founded by the Federal Government of Nigeria and jointly coordinated by I.T.F and N.U.C. The industrial Training Fund (I.T.F) established student industrial work Experience scheme (SIWES) in 1973 to solve the problems of lack of adequate practical skills preparatory for employment in the industries by Nigeria graduates of tertiary institutions. The scheme was designed to expose students to industry based skills necessary for smooth transition from the classroom to the world of work and enable them develop occupational competencies so that they can readily contribute the quota to national economic and technological development after graduation. It offers 12  students of tertiary institutions the opportunity of being exposed familiarized and exposed to the needed experience in real time job demands. 1.2 Aim and Objective of SIWES The aim of SIWES is to bridge the identified gap between knowledge acquired in the classroom and the expertise required by industries. Specifically, the objectives of the Students industrial work experience scheme are to: i. Provide an avenue for students in Nigeria Universities to acquire industrial skills and experience in their course of study. ii. Prepare students for the work situation they are likely to meet after graduation. iii. Expose students to work methods and techniques in handling equipment and machinery that may not be available in their Universities. iv. Make the transition from the university to the labor world easier and thus enhance students contact for later job placement. v. Provide students with an opportunity to apply their theoretical knowledge in real work situation, thereby bridging the gap between universities and actual practices. vi. Enlist and strengthen employer’s involvement in the entire educational processes of preparing university graduates for employments in the industries. 13 CHAPTER TWO: THE ESTABLISHMENT 2.1 Description of dangote sugar refinery Dangote Sugar Refinery Plc (“Dangote Sugar” or “DSR”) is a household name in the sugar refining sector of the Nigerian Food and Beverage Industry. Our entry into the sugar business is dated back to the 1970s with the import and sale of sugar by our parent company, Dangote Industries Limited. Today, Dangote Sugar is a leading brand that has made a remarkable impact on the Nigerian sugar sector. Our sugar refining facility at Apapa is the largest in Sub-Saharan Africa, with 1.44MT per annum installed capacity. Dangote Sugar is the major supplier of refined sugar to consumers and industrial markets in Nigeria, and strategically positioned to serve the regional markets through exports of its finished products. We refine Vitamin A fortified granulated white sugar packaged in 50kg, 1kg, 500grams and 250grams for direct consumption under the brand name “Dangote Sugar”, as well as the unfortified white sugar for industrial use. Our “Sugar For Nigeria” Project. Dangote Sugar Refinery Plc, is an integral part of the Federal Government of Nigeria’s National Sugar Development Master Plan. Our goal is to achieve the capacity to produce 1.5 – 2.0 million tonnes of refined sugar annually from sugarcane plantations covering more than 150,000 hectares of land across a number of sites in Nigeria. This step will move Dangote Sugar from a port-based refining to fully integrated sugar production within Nigeria, thereby helping Nigeria to achieve self-sufficiency in sugar production, and create over 100,000 new employment opportunities. 2.1.1 location and Brief history about Dangote Sugar Refinery The Dangote Sugar Refinery is a subsidiary of Dangote Group Located in Lagos State, at Nigeria’s largest port, The Apapa Wharf. The company commenced business in March 2000 and the Sugar refining plant was commissioned in 2001, with an initial capacity of 600,000MT p.a. The company imports raw sugar from Brazil and refine it into white granulated sugar which is divided into two types; FORTIFIED and NONFORTIFIED Sugar. The fortified white sugar contains Retinol (vitamin A) while the non-fortified white sugars are for industrial use and it is not fortified with retinol. Dangote Sugar 14  Refinery PLC is in the business of refining white sugar using new technology of ION EXCHANGE RESIN(I.E.R). The Dangote Sugar Refinery has excellent facilities designed and installed by TATE and Lyle for production of refined sugar. TATE and TYLE is the largest sugar refinery in Europe and its refining technology is regarded as one of the best in the World. The company’s operation comprises of two key business areas; refining of raw sugar imported from Brazil and marketing and distribution for direct consumption and industrial needs in compliance with the National Agency For Food Drug Administration and Control (NAFDAC) Policy, which makes the fortification of staple food mandatory in Nigeria, Dangote Sugar Refinery PLC produces and packages fortified refined white sugar in 1kg, 500grams, 250grams and 50kg bags for direct consumption under the brand name DANGOTE SUGAR as well as the unfortified white sugar for industrial use and sells its product across Nigeria. Interestingly, D.S.R. is one of the very few sugar refined in the world that produces RETINOL fortified white sugar at its Apapa factory under strict NAFDAC policy. OBJECTIVES OF DANGOTE SUGAR REFINERY Touching the lives of people by providing their basic needs. To become a global, integrated, low cost producer focused on maximizing long term shareholder returns while establishing a leading presence in domestic and regional African market. 2.2.1 Vision and Mission Statement of Dangote Sugar Refinery Our vision is to be a world class enterprise that passionate about the living of the general populace and high returns to stakeholders thus, our vision that our actions be driven by concern for our community and stakeholders needs. 15 Our business mission is to touch the lives of people by providing their basic needs. We seek to deliver the mission and achieve the vision through the following goals. 1. Commitment to customer satisfaction and enduring relationships 2. Deep commitment to staff well-being in employment practices 3. Market image of producer of high quality to products and services and good price performance. 4. Superior profitability, liquidity, earnings and growth. 5. Market leader 6. Reputation for high level of social responsibilities and sound ethical practices. 7. Regular new product lunching. 8. Internationally competitive Organization. CORE VALUE: To succeed we must respond to the needs of our stakeholders as individuals and as a business. We have identified certain behavioral characteristics that will help us achieve this growth. The four core values – customer service, Entrepreneurship, Excellence, and Leadership along with their supporting elements define how we want to conduct our self and our business. 16 2.2.2 Organogram of Dangote Sugar Refinery 2.2.3 Overview of Dangote Sugar Refinery’s Refining Process Dangote Sugar Refinery (cap: 4000MT/day) is committed to the production; sales and distributions of quality refined, granulated sugar that meets and comply with relevant statutory, regulatory & customer requirements using the best raw materials, exceptional resources & processes based on world class standards that guarantee stakeholders’ satisfaction. Our raw material is the Raw Sugar which is imported from Brazil. Raw Sugar is derived from Sugar cane and Sugar beet. Raw Sugar factories crush the cane to produce a juice, which is chemically treated, evaporated and boiled to produce 17 crystals. The crystalline sugar can be sold as raw sugar or further refined in refineries to make White sugar. Sugar Refining involves the conversion of raw sugar (Brown) to refined (White) Sugar by the removal of colour & mineral impurities, fortification, through biological, chemical & biochemical processes. During the process of Sugar refining, some reactions takes place. They include: TaloPhosphatation reaction Neutralization reaction Ion exchange reaction Some Separation and Purification techniques are used. They include: Filtration Ion exchange Resin Crystallization Centrifugation Evaporation While at Dangote Sugar refinery, I was able to learn at the departments below: Process Department Water Treatment Plant Boiling House Quality Assurance Department 18 CHAPTER THREE: DEPARTMENTS/SECTIONS IN DANGOTE SUGAR REFINERY. Process Flow Diagram of Sugar Refining Process 19 3.b Departments/Sections in Dangote Sugar Refinery In Dangote Sugar Refinery we have different sections which work together in order to achieve a successful running of the organization. 20 These sections shall be briefly discussed in the paragraphs below; 3.1.1 Process Department The word Process means the performance of some composite cognitive activity or a particular course of action intended to achieve a result. The process department is one of the major sections in the refinery as they deal with the major refining process taking into consideration a lot of factors like flow rates, temperature, pressure, brix, pH, color, turbidity, reagents used etc. The sugar refining is done by the process department via the sub units listed below in accordance which would be explained further in this report. Very High Polarity Unit (VHP) Talo Clarification Unit Ion Exchange Resin Unit (IER) Pan Boiling Unit (Crystallization) Centrifugal Unit Drying/Rotex Unit Sugar Fortification Unit (Vitamin A) Bagging/Packaging Unit. The Process department is regarded as the BRAIN of the refinery. 3.1.2 Engineering Department This department, which is regarded as the refinery's "heart" since it maintains the flow of refining operations, is quite large. This section handles construction, air conditioning, automated control systems, welding, and power generating, among other tasks. The Engineering Department plays a lot of role in other departments be it minimal or maxima in the refinery as it tends to proffering solutions to any engineering problems. It is sub-divided into the following units; Maintenance, Robson, Water Treatment, Boiler House, Power House, Electrical, Mechanical, Instrumentations, Mechanical Workshop, AC workshop, Utility, Civil 21 3.1.3 Administrative Department This section is concerned with the welfares of the whole refinery ( i.e staffs, customers, equipments etc ). The Administrative Department is one which every reputable company should have as they tend to ensure a smooth running of the company. In Dangote Sugar Refinery the Admin/Human Resource (HR) Department helps to put down on paper the legal frame works presented to staffs, company or customers. They also tend to recruitment of Graduate Interns, Industrial Training Students, Contracted Staffs, Casual Workers etc. The Admin Block Stands on its own as it houses some of the highly designated officials in the refinery. The Admin Department is divided into different sub units which includes; Human Resource Unit, Public Relations Unit, Health Safety & Environment Unit & Maintenance Unit 3.1.4 Finance Department As the name signifies this section is concerned with the monetary policy of the people and the environment. In Dangote Sugar Refinery, the finance department is the ones in charge of delegation and distribution of cash. Under this section is the Account and Records, in this section they take the records of the accounts of each individual so as to be able to forward their wages directly in due time 3.1.5 Quality Assurance Laboratory This is a vital and necessary department in Dangote Sugar Refinery as they tend to set standards after series of analysis to aid a continuous and good refining process. In the Quality Assurance Laboratory, policies, standards, methods, regulations, laws, techniques, specifications and operating procedures for monitoring the quality of production at every stage of the process is set also, the daily or hourly monitoring of production for conformance to the standards and specifications set under a quality assurance 22  system. The most obvious reasons why quality assurance is necessary and important in Dangote Sugar Refinery is that the quality of the product(sugar) the consumer receives is determined to a great extent by what goes on in the factory and how well the factory is under regulation, inspection, monitoring and control. In Dangote Sugar Refinery, the Quality Assurance Department is divided into the following sub-sections; Raw Material Control, Process Control, Special Analysis, Effluent Control and Records. 3.1.6 Materials Department The Material Department are the ones in charge of the all a material brought into the refinery. Here, they receive the desired product, check for faults or any abnormalities/irregularities. If none found, they its been kept in the store and ready for usage at any point in time otherwise, it been returned to the supplier for a proper adjustment or replacement most likely. In Dangote Sugar Refinery the Material Department is very necessary because they have in stock replaceable part of equipment and tools. 3.2 Detailed explanation of the Process Department In Dangote Sugar Refinery Process Department different sections which work together in order to achieve a successful running of the organization. These sections shall discussed in the below; VERY HIGH POLARITY (PRE-MELTING)/MELTING DEPARTMENT This stage is the first unit in Dangote Sugar Refinery and is also known as the VERY HIGH POLARITY (V.H.P) Stage. The pay loaders conveys the raw sugar into the Oban pan which have a hole underneath that allows sugar to drop on the belt drag out there is a magnet which magnets any metal found in the raw sugar before it goes to the elevator. The elevator, which have a bucket 23 inside now transfers the raw sugar to the silo (V.H.P. sugar hoppers) then the screw drag out conveyor drags the sugar to the pre melting tank which have a sever that sieves all the unwanted particles from the raw sugar. Inside the boiling tank there is a rod stirrer that spins around to dissolve the sugar once it gets to the tank to avoid clots/lumps of sugar. The water used in boiling the sugar is called sweet water after boiling the slurry pump will open and transfers the liquor to the next stage. Expected Brix here is 66-67. At the melting stage, detections and corrections of the carryovers done in the first stage is achieved. If the brix is too high or too low this stage will report to the first stage and they will make amendment. They use steam to control the brix, the higher the steam the lower the brix and vice versa. There is Lin catchers here that further detects the carryover dirt from the first stage and then trap them. At this stage it is assumed that the sugar has been completely dissolved before it goes to the next stage. N.B: At every stage there is an expected range of brix. Expected brix here is 62-64. 24 25 TALO-CLARIFICATION UNIT This is where the Dangote Sugar Refining unit place more emphasis in removing the impurities present in the melted liquor, this stage is an essential part of the raw sugar processing. Taloclarification is the removal of color and turbidity from melted liquor through the process of flocculation, floatation and separation techniques. The main objectives here is removal of 90% of turbidity and 40% of color. The Taloclarification flow process is as explained further in the subsequent paragraphs. a. Stage One: Temperature Rising This is the first step to be carried on the melted liquor in order to achieve a high degree of responsiveness to chemical reactions. At Dangote Sugar Refinery this step is done by passing the melted liquor through a shell & tube steam injection heat exchanger which helps to raise the temperature to about 85oc. However, it is sometimes difficult to attain the desired temperature hence, a recycling techniques is employed. b. Stage Two: Chemical Reactions This step is a paramount one as it is a pre-separation process and tends to aid separation of coloration and turbidity by flocculation and floatation. At Dangote Sugar Refinery, this step is carried out in a 3chambered reaction tank where the 1st is the chemical addition chamber, 2nd is the mixing chamber and lastly the floatation chamber. These will be explained further in the subsequent paragraphs:  1st Chamber: As said earlier in here the chemicals are added to the melted heated liquor, these chemical helps in neutralizing the liquor also coagulating the sediments (dirt’s referred to as SCUM) for seperation. The chemicals include; 26  PHOSPHORIC ACID(H3PO4): This is the decolorizing agent with active component P2O5 which is unstable and is 61.6% of 85% food grade H3PO4. The acid reduces the pH of the liquor, thereby making it acidic. In sugar cane, Phosphates are organic as well as inorganic. The inorganic phosphate exists in the form of Phospholipids, Phosphoprotein, Nucleotide phosphates and Hexose phosphates. Only free phosphate ions take part in clarification, and as adequate quantity of phosphate ions is not present in the liquor, inorganic phosphate ions in the form of Phosphoric acid has to be added.  HYDRATED LIME (Ca(OH)2 ): It is the actual amount of calcium that would form saccharate and react with the phosphate to form flocs. It is introduced into the acidic liquor to increase the pH to between 6.9 and 7.3. Its active component is CaO, but before it can be used, it is dissolved in water (Milk of lime), then mixed with unclarified liquor. This mixture is called “Lime Sucrate”. Alternatively, Quick lime can be used, but Hydrated lime is used for its cleanliness, convenience and purity. o The reaction of phosphoric acid and lime produces a calcium phosphate precipitate (primary floc) which adsorbs colloidal and colored material to its self. o The Calcium phosphate formed from the above reaction is known as “Scum” (not soluble in water) which can be used as fertilizer.  TALOFLOC (Magna LT31): This is an aqueous dimethyamine polymer (1,2-ethanediamine polymer with 27  chloromellyloxirane and N-methylamine). It is a decolorizing agent which is in liquid at ambient temperature. The colour removed contains mostly cationic compounds and is attracted to Talofloc which contains mostly anionic compounds. The addition of talofloc into the liquor forms aggregates called “flocs” from the colourant particles that are distributed through the liquor. Equation of the Reaction 3Ca(OH)2 + 2H3PO4 CA3(PO4)2 + 6H2O  2nd Chamber: This is the mixing zone, here the chemicals added in the 1st chamber would be mixed to achieve uniformity via an electric motor driving agitator  3rd Chamber: This the final chamber in the reaction chamber where the floatation takes place via the addition of a floatation agent known as Taloflote and the introduction of air through the bottom of the tank so as to aid uniformity of mixture via bubbling.  TALOFLOTE (Magna LT25): This is a “floatation” agent (Diazo amino benzene) added prior to clarification. It coagulates the flocs to form a single (scum) mass under aeration (the air gives the flocs buoyancy). Taloflote, because it is hydrophobic, lifts the scum and moves to the top, leaving the liquor at the bottom., making the scum less dense. Taloflote is used: o To increase the settling rate of insoluble solids. o To increase mud volume. o To produce good 28  clarity for clarified liquor. o To produce good filterability of mud. c. Stage Three: Clarification In this stage the turbidity is been scrubbed off with the aid of a cylindrically shaped open-end tank with a motor driven horizontal agitator with blades and capacity of about 20m3 called “CLARIFIER”. After the liquor leaves the reaction tank it enters the clarifier, the scum (dirt’s/turbidity) is been lifted up to the surface of the clarifier via the aeration chamber situated at the center of the clarifier through its bottom. The denser matters (scum) been lifted up is then scrubbed off through a channel which is then directed to the scum tank. This method is very much efficient due to the addition of the chemicals at the earlier stages hence proves to be very vital in the clarification process. the liquor from this section is called the “clarified liquor”. d. Stage Four: Filtration This is the final stage in the Taloclarification process, this stage is achieved by passing the clarified liquor through a series of DBF’s (Deep Bed Filters) for the entrapment of more turbid materials. The DBF is also a cylindrically shaped but close tank of capacity of about 5m3 which aids the filtration process via its filter aids which is a nine layer gravel of different sizes as shown in fig 3.2. The liquor is passed through the top of the DBF and it flows down each layers of gravel leaving behind some of the escaped insoluble suspended particles. When pressure reached at 1kg/cm2 then backwashing is automatically starts. This is the first filtration that is carried out on the liquor and very essential because it helps to keep the liquor less turbid and ready for the next stage. 29  e. Stage Five: Scum De-sweetening This is a 3-staged extraction process with similar processes of the stage three clarifier (but smaller in size) which involves the use of a cylindrical open end tank with a motor driven agitator (scrapper). In Dangote Sugar Refinery, this stage is very necessary because it involves the extraction of sucrose content The Factors Affecting Clarification Are:  PH It affects the colour of sugar. When the pH is high, there would be increase in colour and when it is low, it would lead to inversion and this means that a reversible reaction would take place because of the present of water which comes from the liquor. The normal pH is within 6.8-7.3. pH Factors in Sugar Clarification pH Causes Effects Low pH Overdosing of Phosphoric acid Inversion Under dosing of Lime sucrate Optimum pH Complete neutralization Good colour removal Good turbidity removal High pH Overdosing of lime sucrate High colour impartation Under dosing of Phosphoric acid 30   Temperature It also affects the sugar as well because when the temperature is too high, there would be caramelization and the colour would be darker and when it is low, there would be high turbidity. Table 3.2: Temperature Factors in Sugar Clarification TEMPERATURE CAUSES EFFECTS Low Temperature Insufficient heating Slow reaction rate High turbidity Optimum temperature Heat at 840C Increased rate of reaction Reduced turbidity Good clarification High temperature Heat above 840C Burning of liquor Increased turbidity  Turbidity When the turbidity is high, there would be difficulty in filtration. But low turbidity is good for filtration. At talo-clarification unit, the brix and pH are being monitored. The brix should be 64% thereabout and the pH should be within the range of 6.8-7.1. It should maintain a neutral ph. Also here, tank) filtered liquor) and tank 401 (clarified liquor) are also monitored to avoid overflow. Tank 401 is a filter feed tank and the clarified liquor is being emptied in there. Tank 401 Deep Bed Filter Tank Tank 409 Clarified Intermediate Filtered Liquor 31 32 Shell & Tube Heat Exchanger used at the Talo clarification Unit 33 Deep Bed Filters (DBF) used for further clarification 34 ION EXCHANGE RESIN UNIT (IER) This section is also popularly known as “DECOLORIZATION SECTION” as its main function is the removal of about 60% of color from the liquor (clarified liquor) via the aid of some anionic resins placed in a closed cylindrical vessel known as cells. In this section we review some of the main features and development of ion-exchange technology used for the decolonization and deashing of the sugar melt refineries. Ion-exchange technology, included in the 1970s, is one of the more recent decolonization processes to be used. It has been installed either in combination with another decolonization process used in refineries. In Dangote Sugar Refinery, we have 8 batteries where each battery contains two cells to make a total of sixteen cells with maximum of six batteries in use at any given time and the other two on standby / regeneration with brine solution. The pressed liquor forms the filters is pumped through resin columns to further remove color molecules not substantially removed by the Taloclarification process. The system incorporates twin columns of polystyrene resins loaded 15 cubic meters per battery are to achieve a two stage (double – pass) Decolorization. PRINCIPLES OF COLOR REMOVAL BY ION EXCHANGE The ion-exchange resins are usually considered to be similar to electrolytes. Most area manufactured from styrene or acrylic polymers and is chemically activated with various functional groups. Cation-exchange resins are activated by negative functional groups such as sulfonates, and anion-exchange resins are activated by positive functional groups such as quaternary ammonium. When in contact with a chemical solution, the ion-exchange resin reacts according to a simple Acid-Base chemical reaction. For a strong actinicexchange resin, 35  Nacl +H-R – Na-R+HCL For a strong anionic – exchange resins. Nacl + OH – R CI – R + NaOH According to the relative concentration of the various ions in the solution and to the affinity of the resin for theses ions, the ion exchange resin will be saturated (from left to right above) or regenerated (from right to left above). The structure of their copolymer (styrenic, acrylic, gel type, macro porous type) The nature of their functional group (sulfonate, quaternary ammonium) Their maximum theoretical and practical exchange capacity Their pK value as an electrolyte The average size and size distribution of the resin beads Their moisture content and density When an ion-exchange resin comes in contact with a complex organic solution such as the melt liquor in cane sugar refining many reactions take place at the same time and in competition. It is usually considered that the removal of sugar colorants by ion-exchange resins is the result of various types of reactions. An ion-exchange reaction between the colorants mostly charged negatively with alkaline pH and the resin functional groups A hydrophobic interaction between the non-polar part of the coloring materials in relation to their molecular weight and the size of the resin pores. 36 : Characteristics of Styrenic & Acrylic Resins Characteristic Styrenic Resins Acrylic Resins Matrix Polystene, macroporous Polyacrylic, macroporous Reticulated with divinyIbenzena Reticulated with divinyIbenzena Functional groups -N+(CH3)3 strong base type 1 Quatermary ammonium, strong Base Mobile ion Chloride Chloride Exchange capacity Minimum 1.0 Eq/L (total) Min. 0.8 Eq/L (total capacity Capacity (CI-form) CI- form Moisture 58-64% (CI-form) 66-72% (Cr form) Density 1.05-1.08 (CI-form in water) 1.05-1.08 (Cr form in water) Average size 0.6-0.8mm 0.65-0.85 mm Activated carbon decolorization systems used previously for decolorization of the melt liquor or work in combination with pre-existing systems. Acrylic resins, having less hydrophobic with non-polar parts of colorants, are more resistant than styrenic resins to high color feed levels. On the other hand, styrenic resins have a higher decolorization rate and better capacity with lower color feed levels. This is why in some existing ion-exchange decolorization plant, one or several beds of acrylic resins resins are used as front decolorization and one or several beds of styrenic resins are used as polishers. ION-EXCHANGE RESIN PROCESS FOR COLOUR AND ASH REMOVAL At temperature of 80 to 85OC. if the sugar solution has not been clarified perfectly, it is highly recommended that a safety filter be used, to avoid plugging of resin beds with suspended solids 37 REGENERATION OF RESINS The sweetening-on, sweetening-off, and regeneration steps use process water, usually condensates or softened water. Sometimes an additional water recovery tank can be installed to reduce the process water requirement by internal way recycling in the regeneration sequences. Up to 40% of the process water can be recycled by optimizing regeneration. First a saturated brine solution is obtained by dissolving NacI crystals in cold water. At ambient temperature the saturated brine concentration is 330 g of NacI per liter. As the efficiency of a neutral brine regeneration is usually not sufficient for complete removal of all coloring materials from the resin, acid or caustic saturated solution must be prepared by using Hcl. And NaOH dosing pumps. Although the preparation of acid brine is very simple, the addition of a caustic solution 35 or 45% into neutral saturated brine must be managed carefully. The impurities contained in the commercial NacI crystals, especially Mg, flocculate in the presence of NaOH into a hazy Mg hydroxide precipitate. Before using caustic brine solution for the regeneration of the resin, it is necessary to incorporate decantation step, usually followed by said filtration. The design of the brine preparation system depends on the impurities content of the NacI crystals commercially available on-site. The brine saturation, basification, and decantation is carried out in a multiple-compartment brine preparation tank which can be manufactured in concrete. All internal concrete walls should be built with an antacid finish. Vertical plastic dissolution tanks 38 installed when high-purity NacI crystals are available. Usually industrial NacI originating from mining water or seawater is used in crystal form because of the expense of refined caustic solutions or refined commercial crystals. The regeneration effluents, containing NacI, sugar colorants, and water, can be divided in two fractions. The first, composed primarily of rinse water and backwash effluents, can be sent regeneration has been performed, or a low pH, 2 to 5 for acid brine regeneration. This effluent must be neutralized before it can be sent to waste, depending on the pH sensitivity of the waste treatment plant. All regeneration effluents are collected at 80 to 85OC and must be cooled before being sent to waste. If softened water is used as process water for the regeneration of the decolorization station, the regeneration effluents can be used to preheat the sift water before regeneration is about 70OC. all heat exchanger surface in contact with brine and regeneration effluents must be made of titanium, as they handle solution at 80OC and very high CI content. The pumps used on brine and effluent circuits are usually centrifugal plastic pumps with magnetic drive or bronze centrifugal pumps. The pipes should be made of polypropylene or fiberglass. The diluted brine circuits and the internal parts of the ion-exchange vessel are protected against erosion by a coating material: soft or hard rubber lining material manufactured by vulcanization, or fiberglass manufactured by vitrification. The membrane valves traditionally used in the past on the piping manifolds are now replaced by butterfly valves with air actuators, much simpler and cheaper to maintain. The butterflies in contact with the regenerant solutions must be made of coated steel to avoid corrosion. 39 PANBOILING FLOOR UNIT At this section, sugar pure crystalline state. A crystalline product, which is virtually free of impurities and low in crystallization is done. A purification process which extracts sucrose out of a liquid state into a colorants’ A, controlled process of separation or extraction. This is done in a cylindrically shaped boiling vacuum pan where the temperature is raised to about 70 – 75oc via steam injection and the liquor is held under vacuum pressure of about (15psi) which gives rise to condensates been sent back to the water treatment plant. The crystallization is achieved by the addition of an organic solvent known as “Slurry”. Slurry is prepared by grinding 1.62kg of white sugar with 3.6litres of isopropyl alcohol in a slurry mill for 2hours. WELL-MAINTAINED EQUIPMENT Leak Proof Pans. Reliable & Accurate Instruments / Controls  Good Pan Circulation. Efficient Condensing and Cooling System. Efficient Vacuum Pump. Leak Proof Valves 40 TECHNICAL TERMS AND MEANINGS High grade crystallization: sugar from fine liquor and high grade run off syrups that are of high purity (>92.00) and low in color (92.00) and low in color (