Eco-Friendly for Derusting of Steel and Iron Components

Introduction

Currently 38 million tonnes of iron & steel products are being produced in our country every year. Out of this a minimum of 10 million tonnes of steel products may need eco-friendly surface pretreatment. The future demand for derusting of iron & steel components for surface preparation prior to surface treatment will be many fold as the iron & steel components are extensively utilized by various user industries, in view of their abundancy, economics and the required properties. By the year 2005, a minimum of 20 million tonnes of iron & steel products may need eco-friendly surface treatment. The extensive utilization / application of the derusting processes (acid pickling, wire brushing, grid blasting & sand blasting) for removing corrosion products on steel and iron components in the long run would result in severe environmental degradation in view of the by products produced during those processes.

Approach adopted in new technology to evade technological gap in the exiting one

The process is electrochemical in nature and can be classified into 2 categories namely a) Immersion Type and b) Brush surface contact Type. In Immersion Type method components of size ranging from tiny & intricate shaped pins, hookes, rivets, fasteners, bolts & nuts to lengthy steel rebars (plain, twisted & pre-stressed) by immersing the steel components in non-acid electrolyte at critical current density, ambient temperature & critical time of operation wherein which maximum desired level of cleaning (100%) is achieved. In Brush surface contact method existing permanent structures of iron & steel such as, platforms, pipelines, girders, steel walls of tanks can be destructed. In this method polished surface is obtained when the structure is in contact with the brush (supplemented by flow of non-acid electrolyte at constant flow) at critical current density, ambient temperature & critical time of operation wherein which maximum desired level of cleaning (100%) is achieved.

Advantages

The process as a whole is eco-friendly & user friendly as there is no major pollutants involved during the operation and even most of the gaseous products liberated during this process are utilized in the cleaning process, unlike the existing conventional methods of both chemical & electrolytic cleaning. The process as a whole is cost effective as the energy consumption involved is very less than the conventional methods. The non-acid electrolyte used in this process can be reused even after several operations of cleaning with proper treatment. A polished surface is obtained by the brush surface contact method on existing steel structures.

Brief description

The extensive utilization / application of the existing derusting processes (acid pickling, wire brushing, grid blasting & sand blasting) for removing corrosion products on steel and iron components in the long run would result in severe environmental degradation in view of the by products produced during those processes. Keeping in the environmental degradation caused by the above existing processes, a novel Eco-friendly process has been developed at CECRI. The process as a whole is eco-friendly & user friendly & user friendly as there is no major pollutants involved during the operation and even most of the gaseous products liberated during this process are utilized in the cleaning process, unlike the existing conventional methods of both chemical & electrolytic cleaning. The process as a whole is cost effective as the energy consumption involved is very less than the conventional methods. The non-acid electrolyte used in this process can be reused even after several operations of cleaning with proper treatment. A polished surface is obtained by the brush surface contact method on existing steel structures.

Applications

Iron & steel components utilized in a) Automobile Industry such as, Water pump body, Radiator Bracket with top tank, Wheel disks, Cylinder Head, MS Channel., Square tube, Chasis frame, & Front Engine Cross Number., b) High Power Transmitter Relay Centre, such as., Dexon Channel, Guy wire-steel rope, Mast clamp, & G.I. pipe., c) Railway bridge such as., Bearing plate, Sleepers hooke bolts, Rail screws, bolt & Nut, fish plate, tie angles, MS rivets, Rail, Tie bar, MS channel, & Pre-stressed concrete reinforcement wire (used in girders)., d) Railway coach (painted portion & partially corroded painted portion0, e) Railway coach Springs, f) Components of carriage & wagons of railways, g) Cast iron pump housing component and heat treated steel bearing plungers of motor industry, and Sheets of MS, cold rolled steel & stainless steels of treated size 6" x 4" x 2 mm and steel rebars - plain, twisted & pre-stressed of treated size 1' x 6mm dia.

Detailed Description

The process is electrochemical in nature and can be classified into 2 categories namely a) Immersion type and b) Brush surface contact type. In Immersion Type method components of size ranging from tiny & intricate shaped pins, hookes, rivets, fasteners, bolts * nuts to lengthy steel rebars (plain, twisted & pre-stressed) by immersing the steel components in non-acid electrolyte at critical current density, ambient temperature & critical time of operation wherein which maximum desired level of cleaning (100%) is achieved. In Brush surface contact method existing permanent structures of iron & steel such as, platforms pipelines, girders, steel walls of tanks can be derusted. In this method polished surface is obtained when the structure is in contact with the brush (supplemented by flow of non-acid electrolyte at constant flow) at critical current density, ambient temperature & critical time of operation wherein which maximum desired level of cleaning (100%) is achieved. The process as a whole is eco-friendly & user friendly as there is no major pollutants involved during the operation and even most of the gaseous products liberated during this process are utilized in the cleaning process, unlike the existing conventional methods of both chemical & electrolytic cleaning. The process as a whole is cost effective as the energy consumption involved is very less than the conventional methods. The non-acid electrolyte used in this process can be reused even after several operations of cleaning with proper treatment. A polished surface is obtained by the brush surface contact method on existing steel structures.

Ecological / Environmental Impact

The process as a whole is eco-friendly & user friendly as there is no major pollutants involved during the operation and even most of the gaseous products liberated during this process are utilized in the cleaning process, unlike the existing conventional methods of both chemical & electrolytic cleaning. The non-acid electrolyte used in this process can be reused even after several operations of cleaning with proper treatment.

Technology Transfer Assistance Offered

Know-how, Pre-production Testing and Optimization, Design Evaluation, Consultancy

Extent of Commercialisation: Seeking to license or sell this innovation

Contact for more information:

Ms. R. Mallika,
Director, Central Electrochemical Research Institute (CECRI),
Karaikudi -630 006,
Tamil Nadu,  India
Tel: +91-(0)4565-427550-59
Fax: +91-(0)4565-427779
Email: cecri@csir.res.in