Background: 

Recovery and recycling are complementary process regimes. The extent of recycling in India can be gauged from the fact that used/bent nails are straightened and reused. Majority of the recovery and recycling units in India are in the un-organised sector involving door-to-door collection, manual sorting/cleaning/grading and packaging before reaching the processing units. Modernisation of the scrap processing though  inevitable, depends mainly on socio-economic factors.  

1.1 Philosophy of recycling:  Recycling is cost reduction coupled with safeguarding the environment and maximizing resource utilisation. Recycled materials cost less due to reduced energy, handling and others in comparison to those for prime materials. Recycling is also  strongly influenced by legislations. The origin of the legislation can probably be traced to greater awareness regarding the environment and dwindling reserves/access of  quality ores/minerals in the developed countries. In developing countries the economic conditions and a large population with lower skill are the leading motivation factors driving the recycling activities.   

1.2 Recycling rate: The recycling rate is the ratio of the scarp arising and the tonnage of scrap being remelted annually. The rate is highest for metals in countries like Mexico, Brazil and India. The proof for such high recycling rate in India can be adjudged from the fact that a scheme for generating electricity by burning garbage was found to be not feasible as collectors removed nearly all the combustibles.

1.3 US and Europe has lower recycling rates than those for developing countries probably due to the large degree of manual inputs required. Japan has the highest recycling rate for aluminium amongst the G-7 countries [1] and meets its requirement of aluminium from recycling  and imported ingots saving energy and reducing environmental degradation. The recycling rate in developing countries can be related to the following:

1. A large size of relatively affluent population generating wastes. 

2. Medium to High degree of industrialization.  

3. Large population of urban poor with low skill or job opportunity.  

4. Strong awareness regarding the recyclability of materials. 

5. Innovation by the industry.  

2.0 Items of Recycling:

The recycled items belong to a large number of categories. The subject of recycling is well researched and established and can be continuously improved upon. As already stated, this article deals with some specific areas of recycling with emphasis on alumina and aluminum and very briefly scans some items related to Iron and steel making and plastics as these may be of interest to the industry as a whole.  

2.1 Recycling of components of Aulmina refining:  Caustic soda used in refining bauxite to alumina is recovered @ 92% and recycled. The high basicity thixotropic gangue material termed redmud, is generated @ 1.6 to 1.8 tons per ton of refined alumina which is about 3 to 4 tons of redmud per ton of primary aluminum. India’s aluminium smelting capacity slated to attain 1 mtpy, will generate about 3 to 4 mtpy of redmud excluding that for alumina meant for export/tolling. Typical composition of redmud is as follows: 

Fe2O3 .. 50-70% 

 Al2O3 .. 10-20% 

 TiO2 .. 1-22% 

 SiO2 .. 4-20% 

 Na2O .. 2-8% 

 CaO .. Upto 12%