Practical Training Report

Steel Melting Shop Grade Limestone Process Plant

Of RSMML

Submitted in partial fulfillment of the requirements

For the degree of

Bachelor of Technology

Mahesh Kumar Inakhiya

(98002033)

Department of Chemical Engineering

Indian Institute of Technology

Bombay

Content

1. Introduction

2. Description of Plant and Processes

3. Project Work

4. Summary

Chapter 1

Introduction

▪ Brief history

Rajasthan State Mines and Minerals Limited (RSMML), formerly known as Bikaner Gypsum Limited formed in the year 1973, is a premier Govt. Rajasthan enterprises, having vast experience in mining and processing of rock phosphate for over 2-3 years and mining of natural gypsum for last 50 years, and are the largest producer of Rock phosphate and Gypsum in the country, and mining and crushing of low silica Steel melting Shop (SMS) grade limestone for last 7 years. Rajasthan State Mines & Minerals Limited, in short RSMML, is one of the leading and progressive undertaking of the Rajasthan State Government. RSMML occupies a place of pride in non-metallic minerals of India. RSMML is a multi-mineral and multi-location Enterprise engaged in mining and marketing of Rock phosphate, SMS grade Limestone, and Gypsum & Selenite and Green Marble. It is not only a market leader in mining and selling of Rock phosphate and natural Gypsum across the country, but also a global pioneer in technology both in open-cast mining and mineral beneficiation of Carbonate Rock phosphate

The limestone unit started in Feb. 1989 with Rajasthan Govt. intention to augment exploitation of high quality limestone required for steel industries. The Govt. of Rajasthan has given 10 sq km area on lease for exploring the minerals.

The details of mining lease presently held by RSMML.

▪ Existent Plants: Locations, Products & Capacities

Division/Unit	Place of mines	Minerals	Location	Lease are in Hectares
Limestone unit	Sanu	Limestone	55 km from Jaisalmer	1000.00
Phosphate division	Jhamarkotra	Rock phosphate	25 km from Udaipur	1370.36
Gypsum unit Gypsum unit	Jamsar Purabsar Khaturi Ballar Deshi Bagder Anandgarh Lunkaransar Thob1 Thob2	Gypsum Gypsum Gypsum Gypsum Gypsum Gypsum Gypsum Selenite Selenite Selenite	25 km from Bikaner 180 km from Bikaner 85 km from Jodhpur 127 km from Bikaner 110 km from Bikaner 195 km from Bikaner 113 km from Bikaner 72 km from Bikaner 111 km from Jodhpur 110 km from Jodhpur	13.00 6243.1 161.55 1000.04 445.93 308.06 275.00 516.00 126.7 263.00

The Sanu limestone mines and the crushing and screening plant are located 55 km NW of Jaisalmer on Jaisalmer-Ramgarh road. The unit is backed with technically sound and motivated work force. Presently it is producing 1300 MT of SMS grade limestone per day.

▪ Capacities of plants

Industrial Beneficiation Plant (Jhamarkotra) – 700 Tonnes per day

Lime Stone Unit (Sanu) – 3.50 lacks Tonnes per annum

▪ Annual Turnover:

Production – 3,81,553 Tonnes

Sales – 6,93,957 Tonnes

Turnover – 21,48,47,098 Rs

▪ Diversification and Expansion:

Fertilizer:

The fertilizer sector is the major thrust area for the Company and proposes to set up a DAP Plant of 800 MT per day using its own Rock phosphate in the joint sector

The Company is also looking forward for entering into strategic partnership with other Companies for setting up down-stream projects mainly in fertilizer sector using Jhamarkotra Rock phosphate.

Cement:

The Company is promoting a number of major cement plants in Sanu area of Jaisalmer district of Rajasthan to make use of fines/rejects generated during the production of Low Silica Limestone aggregates of specified sizes.

Infrastructure:

RSMML as a major partner in joint venture proposes to lay a 56 KMs. long broad-gauge rail link costing around Rs. 100 Crores to connect the Low Silica Limestone deposits at Sanu to the nearest railway station and link it to the National Railway grid. The railway siding will facilitate speedy and low cost transportation of produce from Limestone mines as well as Cement Plants and to bring back coal and other industrial materials

Lignite:

The major diversification is likely to be in the mining of Lignite in Kasnau-Matasukh area of Nagaur district, Rajasthan. Another possible area is Barsinghsar in district of Bikaner, Rajasthan.

Power:

RSMML has already tied up with M/s Hindustan Zinc Ltd., A Govt. of India Undertaking to set up a 100 MW fuel based Thermal Power Plant.

Expansion:

(i) RSMML is in advance stage of initiating actions for expansion of Beneficiation Plant capacity and Rock phosphate mining operations at Jhamarkotra

(ii) RSMML proposes to add a number of new Gypsum mines and Gypsum production will progressively be raised to about 2 million MT from the current level of 0.9 million MT per annum.

(iii) The Selenite mines near Thob in Barmer district are also being expanded

(iv) RSMML is also establishing a 4.9 MW wind power project near bada bag Jaisalmer.

▪ Organizational chart

Unit head

Personnel & Administration Finance & Accounts Mechanical Mining

Electrical HEMM CSP DQC

The organization of Rajasthan State Mines and Minerals Limited is headed by Unit Head, usually, Chief Manager.

Personnel & Administration: This department deals with the general administration, welfare and personnel matter of the employees.

Accounts: This department takes care of the financial matters of organization. This is responsible for maintaining accounts etc.

Mechanical Department: this is at operational unit. A senior manager heads it. Following sections report to Sr. manager.

(a) Electrical: - Electrical work and electrical maintenance.

(b) HEMM: - Heavy earth moving machinery. It controls the repairing and maintenance of machinery.

(d) DQC: Dispatch and quality control: it deals with dispatching of finished products by checking their quality level.

Mining: This department includes all the mining operation right from the ground preparation to back filling and leveling of rejects.

The main users of the products are:

Steel Authority of India Ltd (SAIL)
Tata Iron and Steel Company Ltd. (TISCO)
Other major steel plants.

Standard product specifications are as follows:

Physical: Size – 30-50 and 40-80 with +/- tolerance of 3%

Chemical: Silica content should be less than 1.3%

The customers accept the product after passing through stringent quality standards.

One of the analysis report of products is attached.

Chapter 2

DESCRIPTION OF PLANT & PROCESS

Crushing and screening Plant (CSP)

The plant is basically a crushing and screening plant (sizing plant). ROM ore from the mine is fed into a ROM hopper through vibrating grizzly feeder (single deck screen). Material of +150 mm is fed to the primary crusher (double roll toothed crusher) after crushing material of +150mm size goes to double deck vibrating screen. Material of

–150 mm size also goes to double deck vibrating screen through belt conveyor. Here primary screening is being done and complete material has been segregated in four different types viz. product, oversize material high grade and low grade reject. Oversize material is fed into the secondary crusher through belt conveyors and put into the cycle of further crushing and screening. High grade and low-grade rejects are conveyed through belt conveyor to their respective hoppers. Finished product is put into further screening to obtain the desired size range of product. Product in three different size ranges is conveyed to the respective hoppers through belt conveyors. The finished products from those hoppers are ready for final dispatches to the market.

List of Crushing and Screening Equipment

Sr. No.	Name of Equipment	No	Capacity	HP
1	ROM BIN	1	120te	-
2	Mechanical Vibrating Grizzly feeder	1	384TPH	120
3	Double Load Toothed Crusher (primary)	1	65/130 TPH	120
4	Double Roll Toothed Crusher Secondary	1	76/150TPH	120
5	Belt Conveyor of 1000 mm width	4	150-340TPH	132(Total)
6	Belt Conveyor of 65mm width	5	80-230tph	132 (Total)
7	Belt Conveyor	4	160-230TPH	40(total)
8	Dust Extraction System	3	-	260 (total
9	Dust Suppression System	2	5 m3/hr	7.5 (total)
10	Double deck V.S.	1	340 TPH	25
11	Double deck V.S.	1	280 TPH	25
12	Double deck V.S.	1	253 TPH	25
13	Tramp Iron Magnet	1	-	9

The detail description of the plant is as follows:

(1) Rom Hopper: Rom is fed into ROM hopper of capacity 120 metric tonne (live capacity). There is a static grizzly with 500X500 mm opening, which is fitted at the top of ROM hopper. Its function is to detain the over size boulders greater than 500 mm. Boulders greater to 500 mm size is subject to manual breaking and the rest material pass through it.

(2) Vibrating grizzly feeder: The mechanical vibrating grizzly feeder is of compact design capable of withstanding heavy shock loads. The main frame is fabricated from carbon steel of bolted construction. It is basically a single deck-vibrating screen with 150 mm circular opening (aperture). Its main function is to convey the material to primary crusher along with primary screening. i.e. +150 mm material is fed to primary crusher for crushing and –150 mm size material is screened out for further screening. It is floor mounted on the main frame and having coil spring mounting assembly located each corner in order not to transmit any undue vibration to the foundation. Its capacity is 384 TPH.

(3) Primary Crusher: It is double roll toothed crusher with one roll as fixed one and another a adjustable. The opening between two roll in general is 120 mm. The speeds of these rolls are 52 rpm. The dimension of roll are; width =1200 mm, diameter =1000 mm. Maximum gap between rolls is 170 mm.

(4) Secondary Crusher: the function of the secondary crusher is as same as narrated for primary crusher, the dimension are same as that of primary crusher, but the normal gap between the two rolls are 60mm. As far as, its operational function is concerned. It is used to crush oversize material so found at the stage of screening. The setting, teeth configuration of roll face and slide wall are selected in such a way so as to minimize the fine (-30 mm) generation.

(5) The material after primary screening at vibrating grizzly feeder and crushing at primary and secondary crusher is taken out from crusher and conveyed to the screen house. This function is carried out by two belt-conveyors namely BC-3 and BC-7. BC-3 carries: material primarily crushed by VGF containing materials –150 mm of natural sizes, BC-7 carries: material after primary an secondary screening. Generally of range -120 mm crushed.

(6) Screens: The main frame is fabricated from mild steel and of bolted construction. The vibrating assembly consists of a shaft on which unbalanced weights are fixed. The spring assembly consist of helical springs, screen desk are of perforated plate type and bolted, torque to screen support frame with necessary lock washers.

In the screen house, there are three double deck-vibrating screens.

(i) Material from BC-3 is fed into vibrating screen VS-5. the top and bottom deck apertures are 56 mm and 35 mm respectively. Here screening is done and the output in three different size ranges viz.

(a) –30 mm termed as low grade rejects containing over burden, sand etc. then the material is taken into low grade reject in with the help of BC-51

(b) Product of size range +30-50 mm. This product is then fed into VS-17, a third screen.

(c) Oversize material is fed into the secondary crusher through BC-10 and BC-12. After passing through tramp iron magnet.

(ii) Material from BC-& is fed into VS-9. The three types of output so generated after screening is as follows:

(a) –30 mm is termed as high grade rejects. This material is fed into high- grade reject bin through BC-61

(b) Product +30-80 mm is fed into VS-17 for further screening.

(c) Oversize material is fed into secondary crusher in similar fashion as in case of VS-15 i.e. through Bc-10 and BC-12 etc.

(iii) At VS-17, finished product is finally categorized into two different size ranges viz.: +40-80 mm and +30-50 mm. These products are conveyed into their respective hoppers by BC-41 and BC-31. BC-21 can also be used to take the product directly from VS-5 to its respective product hoppers.

Important Parts in CSP:

(i) Impact idlers: these idlers are situated at the receiving and of B.C. its main function is similar to that of shock absorber means with the help of these shock/impact is neutralized end. These are idlers and have a rubber layer over it.

This layer plays the role of shock absorber and this is the big difference between impact idlers and simple idlers.

(ii) Drive pulley: This is basically a drum pulley a rubber layer with grooves over it, this is generally located at discharge point with its prime mover. The design is so as to provide necessary functional forces to drive the entire B.C.

(iii) Skirts boards: This is located at the receiving end of B.C. its function is to check the spillage likely to occur at its receiving end. These are metal plates welded and bolted in such a fashion to cover the B.C. (up a length of approx. 1 m) and discharge chute.

(iv) Rubber liners: these are bolted with counter sunk bolts to the inner parts of discharge chutes and other transfer points.

The aim to provide rubber liner is to avoid:

(a) Further breakage of material

(b) Eliminating noise pollution, which is generated by the impact of material with metal parts.

(v) Dust Extraction System: with the help of this system, dust so generated, is not allowed to disperse in and near the work site/generation point. The function of the system is as follows:

(a) Suction of duct is done with the help of negative pressure created by compressors.

(b) Sucked dust, with the help of ducts taken to filter bags where it is trapped into it. The remaining dust particle escaped, such trapping is taken released into the air by stack (chimney) at the height of around 10 to 15 meters.

(c) After certain gap of time, the pressure in the filter bag releases and the trapped dust dropped into the respective B.C.

Dust Extraction system is provided in three locations.

(i) Crusher house

(ii) Screen house

(iii) Load out bins

(vi) Tramp Iron Magnet: It is located at discharge of belt conveyor. It is capable of extracting magnetic material of about 5 kg weight from a height 300 mm. It is of electromagnetic type suitable for 1000 mm belt width. The magnet body is welded steel construction of high permeability. The standard excitor coil consists of an aluminum/copper conductor. Its mounted on the height of 300 mm and its capacity is 150 TPH.

Specifications:

(a) Vibrating Grizzly feeder:

(i) Feed Size: 500 mm

(ii) Capacity: 319 TPH (operating)

389 TPH (design)

(iii) Type: Mechanical vibrating

(iv) Size: 1500x4000 lg

(v) Feeder width: 1500 mm

(vi) Feeder length: 4000 mm

(vii) Feeder RPM: 815

(viii) Motor: 22 kW

(b) Crusher:

(i) Roll diameter: 1000 mm

(ii) Roll width: 1200 mm

(iii) Roll speed (moveable): 52 rpm

(iv) Roll speed (fixed) : 52 rpm

(v) Normal gap between rolls:

Primary crusher: 120 mm

Secondary crusher: 60 mm

(vi) Motor: 1500 rpm

(vii) Electric motor power: 2x45 kW

(c) Vibrating screen:

Item	Vs-5	Vs-9	Vs-7
Capacity	340	280	253
Feed Size (mm)	-150	-200	-80+30
Dimension in mm	1800x1500	1800x1500	1800x1500
Dia. Of circular motion	8 mm	8 mm	8 mm
Inclination of screen	15^o	15^o	15^o
RPM	1460	1460	1460
Motor attached	25	25	25

Chapter 3

Project work

The plant in which I had done my Practical training is a crushing and screening plant . In the project work they told me to visit their Rock phosphate divisions Industrial Beneficiation plant (IBP) at Jhamarkotra (Udaipur), that is the plant in which the first stage is the crushing and screening of rock phosphate and second stage is Beneficiation process that is to increase the P₂O₅ content.

The upgradation of phosphate ores containing carbonate gangue (waste) is one of the toughest problems. The low grade (16% to 18% P₂O₅) Jhamarkotra phosphate ore is containing dolomite carbonate gangue. The process to upgrade this ore was initially developed by IBM at laboratory scale. Later RSMML established a pilot plant of 200 TPD and tested the process for eight years. Having refined and perfected the technology, a commercial plant of 1500 TPD was established and started during the year 1992-93. The technology is unique and has no parallel in the world.

Phosphate ore having 16 to 18 % P₂O₅, 10-12 % MgO and 4-6 % SiO₂ is being upgraded to +34 % P₂O₅ concentrate at +80 % P₂O₅ recovery. The major minerals are sedimentary cryptocrystalline apatite (collophane), dolomite and quartz or quartzitic minerals. The ore from the mine is crushed t –15 mm size. The crushed ore is wet ground in a ball mill in closed circuit with primary hydro cyclones. The primary cyclone over flow is classified into finer and coarser fraction through a cluster of secondary hydro cyclones. The overflow of secondary cyclones hydro cyclones is taken to bulk thickener. The underflow of secondary cyclones is taken to bulk floatation circuit. The froth product of bulk circuit contains phosphate and dolomite and the tails contain mainly silica, which is a waste product. The tail of bulk circuit is 6-8 % by weight of the feed to mill and contains 12-14 % P₂O₅. Soap (sodium oleate) is used as collector in bulk circuit. The bulk concentrate (having phosphate and dolomite) is pumped to bulk thickener.

The bulk thickener underflow is drawn at 1.8 to 1.6-pulp density and taken to acid circuit, where floatation of dolomite is carried out at 5 pH using sulphuric acid and phosphoric acid is used as depressant for phosphate minerals.

The phosphate minerals collected as chamber product (tails) of acid circuit contain +34 % P₂O₅ at a weight recovery of 42±2 % of the mill feed. The carbonate froth is approximately 50 % of mill feed by weight and contains 6-8 % P₂O₅.

Plant operation

The 1500 TPD plant is running at 100 % capacity and produces 1.8 Lac M.T. of +34% P₂O₅concentrate treating around 4.25 Lac M.T. of low grade ore.

Phosphate concentrate produced pre day is 600 TPD.

Main equipments of IBP are as follows:

(a) Ball mill:

(i) Size – 3300 mm (f) x 4200 mm(L)

(ii) Capacity- 36 TPH

(iii) RPM –16-18

(iv) Motor –600 KW, 1500 RPM

(v) Grinding efficiency- greater than 90% but less than 95 %

(b) Bulk thickener:

Its size is 20 m (f) x 3 m (H).

Its size is 300 cubic feet. It is used in the separation of waste particle like silica by adding of oleate and air.

(d) Phosphate thickener:

Its size is 24 m (f) x 3 m (H)

(e) Filter:

Filter is a Belt Drum Filter

(i) Size – 3660 mm (f) x 6510 mm (L)

(ii) RPM- .22-1.3

(iii) Cake building zone-70^o

(iv) Drying zone- 180^o

(f) Pump:

(i) Motor RPM- 960

(ii) Power- 132 KW

(iii) Capacity-4800 m³/hr

(iv) Suction vaccume-600 mm Hg

(g) Blower:

(i) RPM- 2900

(ii) Power- 325 KW

Sulphuric acid addition:

3000-4000 cc/min. at pH 5 at feed rate of 28-32 TPH

Phosphoric acid addition:

600-1100 cc/min. at feed grade of 15-20 % P₂O₅

Oleate addition:

6000-8000 cc/min. at feed grade of 15-20 % P₂O₅

Summary

The plant, which I have worked in, is a crushing and screening plant, which produces a special grade Limestone called Steel Melting Shop (SMS) Limestone from Sanu mines in Jaisalmer district, Rajasthan. It is a sophisticated Crushing & Sizing Plant, which operates to produce final products of different sizes to meet varied size requirement of the giant Steel Plants like ‘Tata Steel’ as well as ‘SAIL’.

In my project work I visited their Phosphate division’s Industrial Beneficiation plant (IBP) at Jhamarkotra (Udaipur). It is a commercial beneficiation plant of 1500 Tone/day feed capacity and produces a Phosphatic concentrate close to 600 TPD. Phosphate ore having 16 to 18 % P₂O₅, 10-12 % MgO and 4-6 % SiO₂ is being upgraded to +34 % P₂O₅ concentrate at +80 % P₂O₅ recovery. It is the only plant of its kind in the world. The Company is now providing this technology globally.

I had presented my report in 4 chapters.

First chapter is the Introduction in which I have given the brief history of company, annual turnover, existent plants, diversification plans of company, and organizational chart of the plant.

Second chapter is the Description of plant and processes in which I have given the details about the process and details of equipment, which are being used in the plant.

Third chapter deals with the summary of my project work. The plant in which I had undergone my practical training during the earlier phase was a crushing and screening plant. The second plant was Industrial Beneficiation plant (IBP). It also deals in with the crushing and screening operation. Additionally, Phosphate ore having 16 to 18 % P₂O₅, 10-12 % MgO and 4-6 % SiO₂ is being upgraded to +34 % P₂O₅ concentrate at +80 % P₂O₅ recovery.