ACKNOWLEDGEMENT It has come out to be a sort of great pleasure and experience for me to be a summer intern in Hindustan zinc Ltd. I wish to express my indebtedness to those who guided & helped me Mr. Lakshman Kumar Pandey, Mr. Amit Sharma, Mr. Shravan Dwivedi & Mr. RP Vaghela. This would not have been made successful without their help and precious suggestions. Finally, I also warmly thanks to all our colleagues who encouraged us to an extent, which made the experience here good.

TABLE OF CONTENTS

1. ABOUT HINDUSTAN ZINCLTD………………………...................................
2. ROASTING PLANT…………..………………………………………………...
3. ACID PLANT……………………………………………………………………
4. LEACHING PLANT………………………………………………………..….
5. ZINC ELECTROLYSIS PLANT……………………………………………..
6. MELTING AND CASTING…………………………………..………………. MAINTENANCE PROCEDURE AND PRACTICES 7. AGIATATORS…………………………………………………………………

1. ABOUT HINDUSTAN ZINC LTD. Hindustan Zinc Limited (HZL) is an integrated mining and resources producer of zinc, lead, silver and cadmium. It is a subsidiary of Vedanta Resources PLC. HZL is the world's second largest zinc production. HZL operates the world's third largest open-pit mine, and World's largest Zinc Mine in Rampura, Agucha in Rajasthan. Other mines with HZL are located in Sindesar Khurd, Rajpura, Dariba, Kayar and Zawar, all in Rajasthan. HZL is also the world's lowest cost zinc producer. HZL operates Zinc and Lead smelters and refineries at Chanderiya (Chittorgarh), Debari (Udaipur) & Dariba (Rajsamand) in Rajasthan and at Vishakhapatnam in Andhra Pradesh. The total metal production was 840,000 tonnes for year 2010-2011. Hindustan Zinc Limited was incorporated from the erstwhile Metal Corporation of India on 10th January 1966 as a Public Sector Undertaking. In April 2002, Sterlite Industries (India) Limited made an open offer for acquisition of shares of the company consequent to the disinvestment of Government of India’s stake (26%) including management control to Sterlite and pursuant to the regulations of SEBI Regulations 1997 acquired additional 20% of shares from public.
HZL is India’s only integrated Zinc Company, operating from mine to finished metal and supplied around 73% of India’s zinc requirements in 2005-06. At the base of the company is the Rampura Agucha mine with its low cost and consistently high grade ore. Zinc Smelter in Debari was started in 1968.The departments as under are: * Roaster& acid Plant * Leaching Plant * Zinc electrolysis * Cadmium Plant * Instrumentation, Mechanical& electrical Plant 2. ROASTING PLANT

In Roasting Plant, oxidation of zinc sulfide concentrates at high temperatures into an impure zinc oxide, called "Zinc Calcine". The chemical reactions taking place during the process are:

Approximately 90% of zinc in concentrates are oxidized to zinc oxide, but at the roasting temperatures around 10% of the zinc reacts with the iron impurities of the zinc sulfide concentrates to form zinc ferrite. A byproduct of roasting is sulfur dioxide, which is further processed into sulfuric acid. Zinc oxide obtained is then sent in leaching plant for further processing.
Firstly, zinc sulphide after ore concentration process is sent to furnace .There at 920-950 degree temperature zinc sulfide combustion takes place producing calcine. Further oxidation of SO2 maintains the temperature range, and then SO3 is sent to acid plant for production of sulphuric acid.HZL has 3 roaster units R1, R2 & R3.Zinc Sulfide Concentrate is introduced directly into the roaster and roasted in a turbulent layer, largely consisting of roasted material especially Zinc Oxide( ZnO). This layer has been heated to ignition temperature by thee preheating device. The desired reaction is maintained by an exothermic reaction of Sulfide Concentrate and air in the turbulent layer.
The surplus reaction heat is taken out of the roaster bed by cooling elements installed in the turbulent layer in the form of evaporator heating surfaces connected to the Waste Heat Boiler. The waste heat is further utilized to generate electricity of about 6MW which is used in the plant.

| ROASTER1 | ROASTER2 | Capacity | 140 tonnes/day | 240 tonnes/ day | Heath Area | 18.5sqm | 35sqm | Air Flow | 9500 | 19500 | No. of nozzles | 1848 | 3500 | Acid | 100M | 200M | Diameter | 4.18m | 6.69m |
Table 2.1.Roaster Specifications

3. ACID PLANT

The utilization of sulphur containing gases after zinc concentrate roasting is carried out at the sulphuric acid plant resulting in marketable sulphuric acid.
For the treatment of Sulfur Dioxide (SO2) in the roasting off-gas, by passing through the Gas Drying Tower, the Sulfur Dioxide (SO2), cooled and saturated with water vapor, comes in direct contact with concentrated acid. Sulfuric Acid (H2SO4) of this concentration is very hygroscopic (absorbs waters) and the gas is practically free from water vapor after leaving the Drying Tower.
After the Drying Tower, the Sulfur Dioxide (SO2) has to be converted into Sulfur Trioxide (SO3) to allow the production of Sulfuric Acid (H2SO4) according to the following reactions:
SO2 + 1/2 O2 → SO3
SO3 + H20 → H2SO4
Gas coming out of hot gas precipitator has 7-8%of SO2 at 330 degree Celsius.SO2 gas is passed through scrubbing tower, which has sedimentation tank and SO2 stripper & wet gas precipitator. In presence of V2O5, oleum is formed which further gives H2SO4.

4. LEACHING PLANT

The calcine is first leached in a neutral or slightly acidic solution (of sulfuric acid) in order to leach the zinc out of the zinc oxide. The remaining calcine is then leached in strong sulfuric acid to leach the rest of the zinc out of the zinc oxide and zinc ferrite. The result of this process is a solid and a liquid; the liquid contains the zinc and is often called leach product. There is also iron in the leach product from the strong acid leach, which is removed in an intermediate step, in the form of jarosite. Jarosite is a waste therefore it is sent to Effluent treatment plant. There is still cadmium, copper, arsenic, antimony, cobalt, germanium and nickel in the leach product. Therefore it needs to be purified.
The basic leaching chemical formula that drives this process is: ZnO +H2SO4→ZnSO4

PURIFICATION
It uses zinc dust, Potassium Antimony Tartarate (PAT) and steam to remove copper, cadmium, cobalt, and nickel, which would interfere with the electrolysis process. After purification, concentrations of these impurities are limited to less than 0.02 milligram per liter Purification is usually conducted in large agitated tanks called Pachukas. The process takes place at temperatures ranging from 40 to 85 °C (104 to 185 °F). The zinc sulfate solution must be very pure for electrolysis to be at all efficient. Impurities can change the decomposition voltage enough to where the electrolysis cell produces largely hydrogen gas rather than zinc metal. That’s the reason zinc sulphide is passed through various thickeners and then hot filter beds where the zinc sulphate goes with the solution as it is soluble. This ZnSO4 solution has pH of 5 which is then sent to electrolysis process.
Zinc calcine, leach solutions and cell house acid are mixed in 11 agitated tanks which are controlled to varied pH, from 2 to 5 , by additions of cell house acid or calcine. Continuous pH monitoring is facilitated by submerged pH cells in controlled tanks.
After leaching, the acid leach slurry is distributed to four 24-m thickeners where the leach residues are separated from the clear zinc sulphate solution. The residues are filtered and washed before being pumped to the Lead Smelter for further processing to recover zinc and other metals. These recovered metals are recycled as a fume to the zinc circuit through the Oxide Leach Plant.
Clear zinc sulphate solution flows continuously from the thickeners to the zinc dust purification circuit. Solution flow rate from this circuit is approximately 450 m/h. An increase in acid concentration from 3 to 4% resulted in a 5% increase in recovery. The higher the concentration of the acid the better the dissolution of the zinc, so zinc is recovered mostly.

5. ZINC ELECTROLYSIS PLANT

Zinc is extracted from the purified zinc sulfate solution by electrowinning, which is a specialized form of electrolysis. The process works by passing an electric current through the solution in a series of cells. This causes the zinc to deposit on the cathodes (aluminum sheets) and oxygen to form at the anodes. Every 24 to 48 hours, each cell is shut down, the zinc-coated cathodes are removed and rinsed, and the zinc is mechanically stripped from the aluminum plates. A portion of the electrical energy is converted into heat, which increases the temperature of the electrolyte. A portion of the electrolyte is continuously circulated through the cooling towers both to cool and concentrate the electrolyte through evaporation of water. The cooled and concentrated electrolyte is then recycled to the cells. This process accounts for approximately one-third of all the energy usage when smelting zinc.
Zinc contained in the purified Zinc Sulfate (ZnSO4) is recovered as metal in the Electrolysis Plant. Zinc Electro-Winning is a method of depositing Zinc Metal (Zn) on the surface of Aluminum Sheet (Al) in cell by passing electric current through the cell. The thickness of Zinc Plating depends on the time spent in the electrolysis cell, the amount of current, and the chemical composition of the cell.
The electrolysis cells are arranged in one electrical circuit of two rows of cells each. The circuit is serviced by two transformer rectifiers that are connected in parallel by Aluminum (Al) and Copper (Cu) bush bars. The cells are connected in series while the Anode/Cathode System in each cell is in parallel.

6. MELTING AND CASTING
The final step is to melt the cathodes in an induction furnace. The furnace is automatically controlled. It is then either cast into pure zinc (99.995% pure) ingots or alloyed and cast into ingots of 25 kg each and 40*40cms .Then they are weighed, bundled up and kept for cooling in the open area for 8 hours.

MECHANICAL MAINTENANCE PROCEDURE AND PRACTICES IN LEACHING - PURIFICATION & ZINC ELECTROLYSIS PLANT.

7. AGITATORS
Agitators play an important role in the surface treatment of drilling fluids. Impellers type mixers provide both axial and radial flow which lowers mud cost and improves mud properties.
Impellers type mixers are basically low shear and low energy, inexpensive to operate and easy to maintain. Low shear mixers are used to suspend and mix mud additives minimizing particle size degradation and polymer shear.
The main function of agitators in the leaching plant is to not allow slurry to settle down so that we can get good percentage of zinc from the solution.
The purposes of agitators are: 1. Ensure the leached products are homogeneously mixed, preventing spot over treatment of chemicals, dilution water or weighing agents. 2. Prevent the pits from getting by keeping active mud system moving when the mud pumps are disengaged. 3. When drilling with weighted mud, properly sized agitators will keep the weighing agents in suspension , minimizing solids from getting in corners or dead spot of the pit.

7.1 THE COMPONENTS OF AGITATORS ARE: 1. Motors with Gear Box. 2. Stool shaft. 3. Bearing. 4. Coupling. 5. Agitators belt. 6. Impellers. 7. Rack & lifting gearbox for Dorr.

7.2 Caution and General Safety Rules:
All personnel responsible for installation, operation and maintenance of this equipment should perform following safety precautions to prevent injury to personnel or equipment damage. * Turn off power, engage lock out, and tag out before performing any maintenance to this agitator. * Do not perform any maintenance or service on the motor before disconnecting the power source. * Discharge all capacitor before servicing the motor. * Electrical repair should be performed by trained personnel only. * Serious injury could result if safe electrical procedures and instructions are not allowed. * Inspect the unit regularly, and replace the worn or damaged components only with the part supplied by the original equipment manufacturer. * Keep hands away and clothing away from moving parts. * The agitators gear box has a designated gear ratio to maximize the suspension of solid in solution. Never attempt to stop or retrieve any object that has fallen into agitator tank.

Start Up
The following are the types of maintenance which can be carried out for maintenance of agitators:

7.3 PREVENTIVE MAINTENANCE:

7.3.1 ON THE MOTOR: * Check the connections are arranged in the exact way and so as to correspond with the supply voltage of the control lines. * The entry of the cable into the terminal board must be insulator and cover must be screw with the care. * Inset overload cut out to guarantee for the damage of the winding * Check the level of grease and lubrication in the component of the motor. * Repair the worn out parts. * Carry out the above procedures daily, weekly, or monthly for proper functioning and to prevent breakdown

7.3.2 ON THE GEAR BOX: * Check the oil level before putting agitators into operations. * Replace or repair the worn out gears * Check the electrical connections.

7.3.3 ON THE IMPELLER: * Do not start the agitators if the impeller is immersed in suit, unless this method of operation has been conditional in the design phase.

7.3.4 ON THE ENTIRE UNIT: * Check the tightening of all bolts and nuts. * Replace the oil in gear box and in general carry out the change of it at 4000 hrs of operations. * Operation of disassembly and assembly of the mechanical seals must be carried out by skilled operators.

7.4 TROUBLE SHOOTING GUIDE Problem | Cause | Solution | * Motor will not start. | * Power problem * Defective motor * Wrong or bad heater | Check electricity supplyReplace motorCheck heaters | * Motor stops running | * Starter tripped * Burned out starter * Over amped | Reset starterReplace heaterCheck amp draw | * Tripped starter | * Bad heater * Over amped * Agitators under sized | Replace starterReplace agitatorsCheck amped | * Whining noise | * Check motor bearing | Replace motor | * Random noise | * Contamination in oil | Drain and replace oil | * Vibration | * Assembly loose * Broken weld | Tighten all boltsRe weld base to tank |

CENTRIFUGAL PUMP Much Hydraulics system employs centrifugal pumps to move fluid through a piping system. These pumps will rely on centrifugal force as the fundamental principle by which they operate. Centrifugal force affects an object or material moving in a circular pattern by causing it pulls away from the central axis or central point of the path along which it travels. This force can be used to regulate the pressure and motion within a pumping unit, and when applied in combination with a number of other centrifugal pumping principles, form an integral part of hydraulic mechanism. Generally a centrifugal pump is based around a casing filled with fluid, usually water. A special unit within the casing exerts fast rotary motion that causes water to spin, generating centrifugal force that channels it through a discharge outlet. Discharged water creates a vaccum for atmospheric pressure to force more water out of the casting. It is a continuous process, dependant mostly on continued rotary motion and a constant supply of water. Most and implementation of these system can very accordingly to capacity and project requirements. SAFETY RULES * Hot or cold machine pats representing a danger must be protected against acciedental contact on site. * Protection against accidental contact for moving parts must not be removed while th machine is in operation. * When operating pump aggregate in a dust laden environment, the surface of the punps and motors must be cleared at regular interval, depending on local condition, in order to maintain the cooling effect and eliminate the possibility of spontaneous combustion. * Leakage from shaft seal of hazardous substance being handled such as explosive , toxic or hot material, must be discharges in such a way that no danger to person or of the environment must be observed. * Danger from electrical energy must be eliminated. MAINTENANCE The safety instruction to be kept in mind while performing maintenance of centrifugal pump as follows: * The pump must not run dry. * The pump must not run in cavitations. * The minimum delivery rate must be always maintained. * The drive motor must not be over loaded. * The shaft shall must have no inadmissible leakage. * The pump unit must not experience or generate any undue vibration. International standards ISO 10816 must be referred to for assessment. * Changes to the normal operating data may indicate faults. The causes must be established. * Installed standby pumps must be started up once a week. * The bearing housing must always be filled with heat transfer oil. If the plant and pump was drained the bearing housing must be topped up with heat transfer oil and bleeded again. MAINTENANCE OF COMPONENTS BEARING: The built-in bearing is maintained free. The nominal service of the bearing is designed for a minimum of 2 years is designed for a minimum of 2 years continuous operation, in accordance with DIN ISO281. The actual usable life may be lower, due to intermittent operation, high temperature , low viscosity, vibration or the like. Monitoring bearing are recommended by means of shock pulse measurement. If the damage to a bearing is detected, the bearing must be replaced. SHAFT SEAL: The built in mechanical seal is maintained free. A maximum dripping dripped rate of 10 g/h may occur during operation and is normal. If the dripping is heavier , the shaft seal must be replaced. A defective shaft seal can cause uncontrolled discharge of pumping liquid . Therefore it must be replaced. AIR FLOW COOLING: The cooling air required for air flow cooling of the casting cover with bearing housing is taken in through the perforated guarded plates laterally attached to the motor stool. Free supply of the cooling air is a condition of safe cooling. Therefore, the perforated guard plates at the motor stool must be dismounted and cleaned at regular intervals. DRIVE MOTOR: The sense of rotation of the motor match the sense of rotation arrow on the pimp. To check the sense of rotation, the motor can be switched on briefly when the pump id full . If the sense of rotation of 3 phase motor can be revesed by switching any two phases. CAUSES AND REMEDIAL ACTION CAUSES REMEDIAL * Delivery head higher than nominal delivery head of pump. SUGGESTIONS: 1. Using Polyether Ketone thermoplastic instead of conventional metals for wear rings and bushing. It is preferred because if it’s thermal stability over high temperature and its self lubricating nature. It also increases seal chamber pressure to prolong seal life. PEEK makes it possible to run much closer tolerances between impeller and the pump casing improving hydraulic performance and reducing energy washing recirculation. 2. Plugging impeller balance holes on single stage pumps. It reduces internal recirculation. It reduces vibration and dramatically reduces cost and time. 3. In service where process condition have permanent changes such as substantially different temperature of pumped fluid, different impeller can be installed to enable normal operation at or closer to the best efficiency point.

12. CONCLUSION It was a great experience to be there in HZL for my practical training. During training period, I certainly learnt a lot about every aspect of this field, right from the working environment to the technical details of various equipments and process. Every industry functions with the help of every branch individual whether computer science, mechanical, electronic etc. Relating to my branch, I certainly learnt a lot about the machine tools especially, lathe, drilling, milling used in the mechanical department. To conclude, I would say that it actually showed the practical side of what I have learnt in my curriculum. Also, it has helped to enhance my sense of professionalism and team work. .

REFERENCES [1] www.scribd.com [2] www.hzlindia.com [3]www.wikipedia.org [4] www.greenerd.com [5] www.engineersgarage.com [6] www.slideshare.net [7] www.thelibraryofmanufacturing.com [8] www.mines.nic.in