Material Recovery Facility - Solid waste management

Presented by: K. Vaithinathan

M.Tech (GET)Reg.No: 13307009

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Material Recovery Facility

Introduction

A materials recovery facility is a specialized plant that receives, separates and prepares recyclable materials for marketing to end-user manufacturers.

There are two types of MRF: Clean MRF Dirty MRF

Principle of Material Recovery Facility

• Mixed solid waste are separated based on their source for recovery of materials.

• The process depends on degree of source separation of waste.

• The nature and design of each unit process accommodate the physical and chemical characteristics of the source material.

• Resource recovery plays an important role in the economies of developing nations

Process involved in MRF

Techniques

Manual methods Mechanical methods

• Electromagnetic separation

• Fluid dynamics• Pneumatics• Others

Processes:

• Size reduction• Air classification• Screening

Manual Processing

• Bulky items (appliances, furniture, etc.) and specified contaminants (e.g., hazardous waste)

• Manual separation is applicable to the removal of contaminants from source-separated materials

• Equipment involved in manual separation of materials usually includes a sorting belt or table, which contains a mixture of materials

• Hoppers or other receptacles for receiving removed items are positioned within easy reach of the sorters.

Manual Processing• Newspaper (700 to 4,500kg/hr/person) • Corrugated (700 to 4,500kg/hr/person) • Glass containers (mixed colour) (400 to 800kg/hr/person)• Glass containers (by colour) (200 to 400 kg/hr/person)• Plastic containers (PET, HDPE) (140 to 280 kg/hr/person)• Aluminum cans

Mechanical Separation

• Size reduction• Glass separation• Air classification • Non-ferrous separation• Screening • Densification• Magnetic separation • Conveyors

Size reduction Technique

• The term “size reduction” has a number of synonyms in solid waste management, including “shredding” and “grinding”.

• Reduces bulky items to particles, the sizes of which are compatible with the processing equipment.

• This uniformity is a requirement of some mechanical sorting systems

Size reduction Technique

• The hammer mill is a type of high-speed shredder frequently used for size reducing solid waste.

• Low-speed, high-torque; flail mill-type shredders; and shear shredders are also used in some cases for size reducing solid waste.

• On the basis of orientation of the rotor -- namely, horizontal and vertical.

Horizontal Hammer mill

Vertical Hammer mill structure

Shear shreddersShear shredder is also used to size reduce mixed waste. This size reduction device is characterized by its high torque and low rpm.

The unit consists of two horizontal, counter rotating shafts. Each shaft contains cutters to tear and shear the material.

In shear shredders, shear and deformation are the primary mechanisms of particle size reduction. The cutters typically operate within a range of 20 to 70 rpm.

AIR classification• Air classification is a process of separating categories of materials

by way of differences in their respective aerodynamic characteristics.

• The aerodynamic characteristic of a particular material is primarily a function of the size, geometry, and density of the particles.

• The suspended fraction conventionally is referred to as the “air classified light fraction” and the settled fraction is termed “air-classified heavy fraction”.

• The confined volume in which the separation takes place is called an “air classifier”.

Horizontal air classifier

Vibrating inclined air classifier

Inclined air classifier

Types of vertical air classifiers

Screening

• Screens are used for achieving efficient separation of particles through dependence on differences between particle sizes with respect to any two dimensions.

• Screening process: Oversized feedstock, Undersized feedstock

Types of Screening

Trommel Screening:• The trommel has proven to be quite effective and efficient for

processing mixed waste and other mixtures where large, flat particles (e.g., paper) and aggregate-type particles (e.g., crushed glass) must be separated.

Types of Screening

Disc screen:• Disc screens have been employed in many waste processing

facilities. The predominant applications to date are effecting the separation of inorganic materials from refuse-derived fuel fractions, from paper materials, or from wood waste.

Magnetic Separation

• Magnetic separation is a process used to segregate magnetic (i.e., ferrous) metal from a mixture of different types of materials, e.g., mixed waste or commingled metal, glass, and plastic containers. The process is technically simple and of relatively low cost.

Aluminium and Glass Separation

• The predominant non-ferrous metal represented in the waste stream is usually aluminium, and it is oftentimes a target for recovery.

• In the case of aluminium, heavy media and eddy current separation are possibilities.

• Eddy current separation is, at present, the more commercially feasible.

• Separation is brought about by the ejection of aluminium particles from a moving waste stream due to the force exerted on the metallic particles as they pass through an electromagnetic flux generated by the equipment.

Conclusion

• By Material recovery facility the Waste management system functions efficiently.

• MRF methods provides recycling of raw materials for Industrial uses.

Thank

you…!