Selected Projects Registered with Industry Canada

Recovery Technologies for Lead & Zinc in India

Description : A C.I.D.A. funded project was undertaken in India in which the objective was to determine the applicability of environmentally clean technologies to the secondary Lead and Zinc Industries. It was found that companies were well aware of the technologies available. The reason for the problems was that the companies were being starved of secondary materials. The Indian government had earlier stopped the import of the secondary lead and zinc materials in an effort to conform to Basel Convention directives. The effect of this action was to exacerbate the problems caused by the extensive ‘backyard smelting' of spent lead/acid batteries. In addition, zinc sulfate, a necessary trace element for human health, was not available to treat zinc deficient soils.

The guidance provided by I.R.M. was primarily to Government agencies. The first stage was to recognize that Basel Convention politics are determined by countries that are trying to prevent the export of their secondary materials. This is irrespective of the environmental conformance of the companies receiving the materials. The Indian Government has since taken steps to lift the import ban. A scheme was proposed to account for the flow of secondary lead within India and this would be the cornerstone of a united effort to channel such materials through government approved facilities. Government and Industry Groups are starting to implement this objective also.


Conclusion : Basel Convention implications for trade in secondary materials (1999). The problem was found to be political rather than technological.



Hydrometallurgical Recovery Facility Operating Below Capacity

Description : A client's hydrometallurgical facility for the recovery of electric arc furnace dust was unable to meet the design capacity due to difficulties with both the process and equipment. The chemical process was significantly modified by I.R.M. making it less capital intensive and much easier to control. Patents have been applied for and this process is expected to be operational at new facilities in 2000.


Solution : Make innovative changes to the chemical process.



Quality Variations in a Key Raw Material for Ceramic Tile Production


Description : A major producer of ceramic tiles in Asia had formulation problems due to the variability in quality of the zinc oxide pigment that was available. A proposal was made for an on-site zinc oxide production facility to manufacture high quality grades. The plant was designed to have a 50% excess capacity so that surplus production could be sold off-site. The design featured the use of immersion burners for zinc melting and regenerative burners for zinc evaporation. This is the most energy efficient and lowest capital cost option for production of high purity zinc oxide pigment.


Solution : High efficiency furnace for zinc oxide production (1994). A complete design for the production of high quality material using energy efficient technology was submitted to the client.



Viability of a Rubber Recycling Project


Description : I.R.M. were approached by a potential investor to determine the feasibility of a recycling project for scrap tires and plastic waste. Rubber crumb and chopped plastic were incorporated into a thermoplastic blend by use of a high energy mixer. The blend could then be molded into a variety of products which previously had been made from new rubber. I.R.M.'s evaluation concluded that the process was technologically and economically viable. Subsequently I.R.M. contributed to the design of the plant to produce the recycled rubber products for roadway uses.


Solution / Conclusion : Feasibility Study - Innovative use for scrap tires and plastic (1992). The project was judged to be economically viable .




Measurement of Zinc Oxide Surface Area by Air Permeability


There are several methods for characterizing the morphology of zinc oxide (or other pigment) but none of them give a complete picture. Scanning electron microscopy (SEM) is the most comprehensive if the image data is further developed to give data on particle size. This equipment is fine for research studies and characterization of a particular material but is much too costly for process control.

Measurement of surface area may be carried out directly or indirectly. The direct method is by BET nitrogen absorption, indirect measurement is by Air Permeability. These methods are very good for ongoing analysis such as in process control but do not give any indication of particle size and shape.

Particle size distribution can be determined by sedimentation or laser scattering methods. The data generated tends to be very dependent on the particle shape and the actual numbers are often different from the other methods.

The mean particle size determined from surface area measurement is usually expressed as m.e.s.p.d., mean equivalent spherical particle diameter. This is the diameter if particles were assumed to be all equal sized spheres.

Each zinc oxide grade should be characterized by SEM but ongoing analysis and process control is most effectively carried out by the surface area measurement. The air permeability method uses the method of Orr and Delavalle. This method applies a correction factor to that used by the Fisher Sub Sieve Sizer equipment which reaches its lower measurement limit at around 1 micron. The method was used extensively, but it suffered a major disadvantage in that it was very tedious to derive data from the mathematical formula. We have generated a program using Microsoft Excel which directly determines the surface area from input data of sample weight and elapsed time. The program can be readily modified for other pigments. The air permeability method uses relatively simple equipment which is very easy to use. In contrast to BET measurement, no commercial version of this method has been produced. Other than the permeability cell, this method only requires simple equipment which Zinc Oxide companies commonly have.

            Correlation with BET measurements is good, however companies using air permeability quickly have more confidence in their own data than with the BET measurements.

The air permeability method is therefore much more cost effective both in terms of capital and operating costs. The time to make an air permeability determination is less than 10 minutes compared to more than 20 minutes for BET.

The BET method also requires liquid nitrogen.


SEM equipment for image observation plus size analysis may cost US$250,000. Generally specialized testing companies and Universities carry out this work and charge around $200 for each sample.

BET equipment costs from $20,000 to $40,000.

Particle size distribution equipment is over US$60,000

 For this Air Permeability method, the cost for the cell, the information package and software is US$2,500. SEM work can also be arranged. For further information, please contact Peter Robinson,