The multipurpose smelting unit MAGMA provides autogenous technology of high-temperature recycling of unsorted municipal waste on a layer of molten over-heated slag that forms from mineral components of waste and fluxes specifically added in the process of recycling.
Temperature of the working space of the smelting chamber over the layer of molten slag is 1800-1900°С and temperature of slag is 1400-1650°С.
Under preselected parameters of waste feeding speed, quantity of molten slag and dimensions of the smelting chamber the process produces "thermal shock", under which the fed waste is immediately heated up to high temperatures that rule out the possibility of formation of dioxins.
In the MAGMA unit, gases stay at 1850°С for 3 seconds. Under such conditions, almost 100% destruction of dioxins and furans contained in the waste delivered to the plant is ensured.
A number of principally new technological solutions are used in processing municipal waste:
- preliminary drying of waste to moisture content 10-15%;
- recycling of waste in oxygen allows to decrease the volume of the off-gases and reach concentrations NOх<80 mg/m3, СО<7 mg/m3.
MAGMA is equipped with highly efficient cooling systems of the unit body, afterburning of CO and recovery of heat from process gases in heat-recovery power boiler.
Off-gases are treated by a multistage processing route:
- “quenching“ of gases for exclusion of secondary formation of dioxins and furans;
- cleaning of gases from hazardous substances.
The waste drying and feeding system, as well as the smelting unit are hermetic, this creates a small underpressure in the working space of the smelting chamber. This ecludes possibility of non-organised emissions of process gases from MAGMA to the environment.
The metal component of waste, when molten and accumulated at the bottom zone of the smelting chamber, as well as excessive amount of slag, is released from the unit non-continuously for subsequent processing into finished products.
In the process of high-temperature recycling of unsorted municipal waste, chemical composition of molten slag is adjusted by adding fluxes for the purpose of further production of cast-slag saleable products without any toxic compounds.
The dust captured in gas treatment facilities is injected back to molten slag where it is assimilated by slag.
Flow diagram of municipal waste processing
Table 1. Comparative performance of waste incineration plants
|MVA Weisweiler GmbH
|Maximum production capacity for wet unsorted municipal waste, metric tons per year||
(1 unit per 300,000 tpy)
(3 processing lines per 120,000 tpa each)
|Waste recycling method||incineration on surface
of molten slag in oxygen
|incineration on burning grate
of power boiler in air
|Waste from recycling process||no waste||toxic ash, toxic dust
of gas treatment
|Heat recovery||heat-recovery power boiler||heat-recovery power boiler|
|Temperature of molten slag||1400-1650°С||-|
|Temperature of gas phase||1800-1900°С||1100°С|
|Construction period, years||2||4|
Magma can be used for remediation of existing municipal landfills.
Table 2. Production figures of high-temperature recycling of municipal waste in the Magma unit
|Output products||Unit per tonne of wet waste||Value|
Production figures are given per ton of municipal waste with initial moisture content 30% and can change depending on morphological composition of municipal waste.
Recycling of unsorted municipal waste by MAGMA gives the following benefits:
- environmentally clean process in accordance with European Union requirements
- profitable production
- waste-free technology