Safety Challenges in the Construction of a Large Water Recovery Plant

Safety Challenges in Construction of a Large Water Recovery Plant at India’s Oldest Ferro Alloy Plant

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Abstract

Tata Steel operates Manganese mines at Joda in Odisha producing Manganese ore which is sent to

the Ferro Alloy Plant at Joda and converted to Ferro Manganese. This Ferro Manganese is sent to

Tata Steel’s Steel Plants at Jamshedpur and Kalinganagar; as well as sold to customers across the

world.

The Ferro Alloy Plant at Joda was commissioned in 1958 and is in continuous operation since. It

currently produces 50,000 MTPA of HC Ferro Manganese in two Submerged Arc Furnaces.

Gas Cleaning Plant (GCP) slurry generated in wet venture scrubbers is collected in slurry pits inside

the plant for drying and subsequent disposal. Because of space constraints, and in order to recycle

the water used in the wet venture scrubbers, Tata Steel is upgrading its GCP slurry handling process

by the installation of a GCP slurry dewatering plant.

Construction of large structures within an operating plant, without affecting operations is always a

challenge. The job is even more challenging, since the plant is 58 years old, with many unmarked

structures, pipes, and cables lying underneath.

This paper discusses how new and unexpected challenges are tackled during the construction of the

Slurry Dewatering Plant without compromising on safe working.


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Background

Manganese is the fourth most widely used metal after iron,

aluminium and copper. While it is used for various

applications, almost 90% is used in the manufacture of steel

for refining and as an alloying element.

In nature, Manganese occurs as oxidized or carbonated

mineral deposits (ores). Manganese Ores occurs as ferruginous

deposits in the Bonai-Keonjhar synclinorium region contiguous

with iron ore.

Manganese is usually added to steel as a ferro-alloy, i.e. a low

melting eutectic compound of Manganese with iron, carbon

and other elements. The two most common ferro alloys are high carbon ferro manganese & silico

manganese. The Ferro Alloy Plant at Joda currently produces high carbon ferro manganese from

Manganese Ores found locally.

Ferro Alloy Plant Joda and the Ferro Alloy Making Process

The Ferro Alloy Plant at Joda was

commissioned in 1958 to supply

manganese alloys to Tata Steel’s plant

at Jamshedpur.

It is India’s (and possibly the world’s)

oldest continuously operating Ferro

Alloy Plant.

It currently has two submerged arc

furnaces, one 9MVA and another

15MVA and produces 50,000 MTPA of

High Carbon Ferro Manganese through

carbo-thermic reduction of manganese

ore as shown in the accompanying

diagram.

Gas Cleaning Plant

The flue gases released during production contain manganese dust and other solid particles which

need to be cleaned before being released into the environment.

This is done by passing the flue gases through a Gas Cleaning Plant containing wet type venture

scrubbers; which use water to coalesce dust particles and let out the cooled and cleaned gases into

the environment.


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Current Process of Slurry Management

The resultant slurry is thickened and transported to sludge pits via a pipeline. The sludge from the

Gas Cleaning Plant is then collected in sludge cleaning pits. Water from the sludge pits percolates

into the ground and contaminates ground water.

As sludge has been declared a hazardous waste by Odisha State Pollution Control Board (OSPCB); its

percolation into the ground needs to be avoided. Moreover, in the process, complete recycling of

water is not possible as a significant amount of water from the sludge pit is lost by this percolation.

Hence, we are in the process of installing a state of the art, Solid Liquid Separation Process plant at

FAP Joda in order to :

a. Meet the statutory norms of State Pollution Control Board, Odisha and compliance to the

conditions laid in the Consent to Operate.

b. Recycle & reuse water

c. Eliminate ground and surface water contamination and the expenditure on account of

impervious lining


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Solid Liquid Separation Plant for Slurry Management

We are setting up a Mechanized de-watering plant with a High Rate Thickener and a Press Filter. The

Plant has the following equipment, :

a. Filter press with accessories,

b. Installation of High rate thickener with accessories

c. Process Automation supplied by the vendor

d. Chemical dosing system with accessories

e. Compressors and related electro-mechanical equipment

f. Standard attachments and accessories.

and, meets the three requirements from OPCB, namely :

a. Cooling water will be completely recycled through recycling from the mechanized dewatering

system (Figure 5 shows the water conservation that will be achieved).

b. The mechanized dewatering system will result in the dry sludge, which can safely be dumped

inside the plant in a manner which would not contaminate ground water. A retaining wall is to

be constructed in sludge dump area.


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Construction Difficulties and How They Were Tackled

Since the plant has had to be retro-fitted to an existing, working plant, there is very little space for

accommodating all the facilities planned. After a lot of deliberations at site and design

improvements, the plant was designed so that it could fit in the space available; between the old

dump hopper and the old thickener. This in itself increased challenges during construction.


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Site Safety Challenges

1. Old Dump Hopper – This Dump hopper building is a very old structure and situated at left of

pit excavated for the new thickener. Due to lack of space, we had to cut the slope vertically

(at almost 90o), so that the thickener base foundation, at a depth of 4 m could be fitted. The

lateritic soil becomes very weak once it rains. As remedial measure, strong shoring was done

to hold the soil slope. We also drilled hollow pipe sections into the ground to ensure stability

of the super structure, the old Dump Hopper Building.

2. Old GCP Thickener area - The structure is also very old and situated at the right of the

excavated pit of new thickener area. By the side of the structure is an old brick walled slurry

trench. The slurry lines in the trench take the thickened slurry from old thickener to the sludge

pits, with no alternate route. Dismantling of the brick walled drain would result in stopping of

the plant operations and a huge production loss. To avoid the loss, we first placed a strong

hollow pipe as an alternate route; then stabilize the trench and created a safe and working

environment for excavating pits for the foundation of the Thickener and Filter Press Buildings.

3. Existing pipe trench for slurry lines to the old slurry pit – Because the slurry trench passed

almost through the middle of the proposed area for setting up major structures of the new

plant; i.e. the new Thickener, the Filter Press and the DG Building; and the leakage of slurry

over the years from the old slurry pipes; the soil bearing capacity of the area was far lower

than the average. Hence, the foundations had to be built deeper, to a level of 4m to reach soil

stratum of good bearing capacity. This deep excavation posed difficulties in slope stabilization

which was tackled through proper shoring with pipe & steel sheet supports to the walls.

4. Live Cables through Project Site – The Ferro Alloy Plant at Joda plant is almost six decades

old and due to a lot of space available then, underground electrical cables have been laid in

an unplanned manner and without proper marking. Old drawings, if available were also lost.

To mitigate the risk of hitting live cables during excavation, we used a live cable detector to

mark the cable path before excavation.

Technical Challenges

1. Very Deep Excavation : Due to the issues cited above, the design team specified a RCC

foundation depth for the thickener & filter press area of 4m. Excavation to a depth of 4m in

soil that is of a reddish-brown lateritic type, mixed with ferruginous nodules, pebbles, gravel

etc. was challenging due to the widely varying soil hardness.


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2. Water seepage : There was frequent water seepage from the top as well as from an

underground aquifer which submerged the excavated pit frequently, requiring frequent

dewatering. Because complete dewatering could not be done, rod binding, pouring concrete

etc. was very challenging!

3. Side Slope Unstable : Due to the water seepage problem, stability of pit slope was of prime

concern. Proper shoring, barricading was done to stabilize the slope and create a safe

working environment.


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Safety Challenges during the Execution and How They Were Tackled

Making the Site Safe from Normal Operations

A. The Jigging Plant

The jigging plant was situated in the old thickener area, where the Solid Liquid Separation plant is

being constructed. The old jigging pit had a very thick RCC foundation. It took a lot of effort and time

to shift the jigging plant to a new location, including re-making the thick RCC foundation to start the

construction work.

B. Various Pipes & Cables

As mentioned earlier, in the almost 60 year old Ferro Alloy Plant, there were many unmarked

underground electrical cables and pipes in the construction area, which needed to be shifted. By

keeping the construction area separate from normal operations, it was possible to reroute the

cables without affecting operations which greatly increased safety during construction.

C. Weather Proofing : A major challenge has been working through the very heavy monsoon period

(June-16 to September-16). To ensure safe working we ensured that no foundation work

(excavation, making of columns etc), electrical work (HT cabling etc.) or erection work was

scheduled during the monsoon period.

Similarly, we ensured that during the very hot period from mid-March to mid-June, when heat

induced incidents are common, there was adequate supply ORS, cold water etc. as well as

rescheduled the work time, as per statutory guidelines, to avoid working between 11am and 3pm

when the temperature peaks.

D. Lack of space, mentioned earlier, has also meant that the work that could have been carried out

in parallel in any other site, has per-force had to be sequenced because of safety and other

execution. Keeping the stores at a different location, away from working area improved safety.

Site Safety

No job is so urgent that we cannot take the time to perform it safely

Mike Shavers, President, Mountain V Oil & Gas Inc


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Safety is not negotiable, and we at Tata Steel, through years of training, efforts and learning from

incidents have made safe working almost second nature.

We jointly develop safe working SOPs, HIRA and training of workmen during the execution of the

job.

Inadequate planning and sequencing of jobs are major causes for onsite incidences; which we

avoided by proper planning & scheduling along with our contractor TENOVA India.

Timely and regular safety audit in the initial stages by external teams helped us greatly in identifying

hazards. Post the audits, we developed many safety protocols, some of them being :

a. Site Safety In-charges from Tata Steel, the engineering consultant and two site safety in-

charges from the execution partners were appointed for the project.

b. Daily tool box meeting conducted at site before start of job where the work to be done, along

with the possible hazards are discussed with each workman. This meeting is attended by the

Project Team from Tata Steel, the Engineering Team and all members of the execution team

of the Contractor and Sub-Contractor.


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c. SOPs (Standard/Safe Operating Procedures) made for each activity. All workmen are trained

on these SOPs as required before start of job during the Tool Box meeting.

d. Check List for daily checking of all equipment : Grinding Machine, Dumpers, Cranes, JCBs, Fire

Extinguishers, Welding Machines, etc. made and followed on a daily basis.

e. Authorized entry ensured at site – with Proper Safety Training and issuing Gate Pass from

security as per norms.


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f. Work permit system implemented at site – Identification of 6 directional Hazards and

Mitigation is a part of the work permit.

g. Use of Personal Protective Equipment (PPEs), as per nature of job is ensured at the site.

h. Labour shed with all facilities (separate kitchen, drinking water, toilets etc.) was the first

structure constructed. A further provision of designated rest areas, with drinking water

facilities, was also provided at site post the audit.

i. Protocols for movement of Dumpers, JCBs, Cranes and other heavy moving vehicles

developed. We have designed the layout in a systematic manner to ensure that all the

activities can be carried out during construction without unwanted hindrances from other jobs

being carried out in parallel.

j. MSDS for all chemicals, including fuel at site and following the listed precautions.

k. Emergency Response Plan displayed at all key locations.


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l. Fire Safety : location of fire extinguishers such that they are easily approachable, having

regular mock drills etc., are also safe behavior that must be implemented at any construction

site.

m. Regular and Frequent Safety Inspections : The first safety truth relates to volume, with

studies showing injuries decrease as observations increase. Hence, we encouraged everyone

to audit the construction site and make observations of hazards, unsafe practices and suggest

improvements which we rigorously ensured were acted upon. We also instituted a system of

inspections in the night (on the rare occasions when work had to be done till late, due to a

casting for example).

n. Inspections by people from very diverse fields : The second safety truth involves the diversity

of observers. Involving observers with different skill sets allows risk to be better identified and

managed. Hence, by encouraging people from diverse fields (including those from “desk” jobs

like HR & Accounts) and different levels (new entrants & trainees to people with many years

of experience) we received feedback which was more comprehensive than if we restricted

making of observations.

o. Driving Ownership : this was one of the most difficult tasks. With identified safety officers

from Tata Steel, the Contractor and the Sub-Contractor, there was a tendency to view that

these safety professionals as owning the safety process, instead of safety being a group effort

which was tackled through regular communication in tool box meetings and review meetings.

p. Encouraging recording of both ‘safe’ and ‘unsafe’ observations : Projects with a high

frequency of all safe inspections are generally at a very high risk for injuries. The reasons

observers may falsely indicate nothing is wrong vary from not knowing how to determine

what is unsafe to fear of reprisal from management or fear that unsafe observations are

perceived as poor job performance. If error, including human error, is viewed as a criminal act


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with penalty, no one would volunteer this information. Hence, we have tried to encourage a

culture of discovery in which we routinely are engaged and empowered to find and fix unsafe

activities, as well as address the causal factors that allowed them to occur in the first place.

q. Recording near misses is again a vital but very difficult task. Near misses have been defined as

unplanned behaviors or events that did not result in injury, illness or damage, but had the

potential to do so. We have recently started a system of reporting and acting on near misses.

r. Ensuring every observation is acted upon and closed is the cornerstone of ensuring safety in

the project site.

Conclusion

Ralph Waldo Emerson, the noted American Poet and Essayist once said, “Shallow men believe in

luck. Strong men believe in cause and effect.” He could be defining construction & process safety.

Having an incident in the workplace is always unplanned, and frequently seems to have occurred

due to a freak coincidence of many events; an accident. However, it is not. Safety is ensured only as

a result of hard work, proper planning, setting up of protocols for safe behaviour, including SOPs;

regular safety audits with attention paid to closing of observations, etc.

We have been both lucky and have worked hard at making the Solid Liquid Separation Plant

construction site safe. Much has been done, but still many lose ends remain. Safety is truly an on-

going journey. We are nowhere near mastering safe construction practices, we remain students.

With this article, we hope that by sharing our experiences and by reading about the experiences of

others in this safety journey, we will remain on the safety improvement path.


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