【Introduction】 Under the dual background of increasing depletion
of mineral resources and continuous upgrading of environmental
protection standards, flash magnetization roasting technology is
setting off a deep change in metallurgical solid waste resource
utilization. The precise activation process for weak magnetic slag,
so that zinc, nickel and other non-ferrous metallurgical processes
in the “scrap iron slag” turned into high-grade iron raw materials,
opened up a new era of efficient use of metallurgical solid waste.
First, the core technology principle unveiled
Intelligent preheating system
Utilizing 600-800℃ high-temperature waste gas generated by the
roasting process, the furnace slag is preheated in a stepwise manner
through a multi-stage heat exchange device. Adopting gas-solid
countercurrent heat exchange design, the temperature of slag is
raised to over 300℃ before entering the reaction zone, and the
heat recovery efficiency reaches 85%, which is 40% energy-saving
compared with the traditional process.
Fluidized magnetization reaction
In the special reaction tower, slag particles of 0.1-0.3mm particle size
form a suspended fluidized bed under the action of high-speed airflow.
The three-stage magnetization reaction is triggered by precise control
of the oxygen concentration (3%-8%) and temperature field (750-900℃):
Dehydration and dehydroxylation (200-450°C): limonite and acicular
ferrite release crystalline water
Crystal reconstruction (550-700°C): Hematite is transformed into
magnetohyperite.
Deep reduction (750-900 ℃): Fe₂O₃ partially reduced to Fe₃O₄
Magnetic separation efficiency mechanism
The magnetic properties of the roasted slag are enhanced by 8-15 times,
and the magnetization rate is increased from 0.5×10-⁷m³/kg to 5×10-⁵m³/kg.
Combined with the high-pressure roller milling dissociation technology,
the degree of dissociation of the iron mineral monomers can reach more
than 92%, and the grade of the magnetically selected concentrate is
increased to 58%-62%, and the grade of the magnetic separation
concentrate is increased to 58%-62%. grade is enhanced to 58%-62%.
Schematic diagram of flash magnetization roaster working principle
Analysis of six core advantages
Adaptability to ultra-fine materials
It can deal with micro-fine slag with particle size <0.3mm (-200
mesh accounts for ≥80%), breaking through the limitation of
traditional rotary kiln on the particle size of materials. Fluidized
bed design makes the micro-powder with specific surface area
of 5000-8000cm²/g keep stable reaction.
Multi-mineral compatible ability
Hematite: Conversion rate ≥95
Limonite: 98% water removal rate
Rhodochrosite: decomposition efficiency 92%
Acicular iron ore: crystal transformation rate of 90%
Breakthrough in energy saving and consumption reduction
With integrated waste heat power generation system, the energy
consumption per ton of slag treatment is reduced to
18-22kg standard coal, which is 55% energy-saving compared
with the conventional roasting process. Exhaust gas recycling
rate of 90%, sulfur dioxide emission concentration <35mg/m³.
Intelligent control system
Temperature field monitoring: 128 thermocouples real-time
feedback three-dimensional temperature distribution
Oxygen concentration regulation: laser gas analyzer updates
the atmosphere data in the reaction zone every 5 seconds
Material tracking: RFID chip realizes the simulation of single
particle movement trajectory.
Compact equipment structure
Vertical tower design reduces height by 60% and footprint by
75% compared to rotary kiln. Modular assembly enables flexible
configuration of a single line with an annual processing capacity
of 300,000-1,000,000 tons.
Significant resource utilization benefits
Zinc leaching slag treatment can obtain TFe ≥ 58% of iron powder,
nickel-iron slag recovery rate exceeded 85%. Every 10,000 tons of
slag treatment creates economic value of 1.2-1.5 million yuan,
and the investment return cycle is shortened to 2.8 years.
Typical Application Scenarios
Zinc wet smelting system
Processing of iron slag generated by PLS purification (Fe
content of 35-45%), iron recovery rate from 40% of the
traditional process to 78%, simultaneous recovery of
residual zinc in the slag (Zn ≤ 0.8%).
High pressure acid leaching of nickel laterite ore
For HPAL process tailings (Fe₂O₃ content of 50-65%), the
nickel content of the concentrate is reduced to 0.08% after
magnetization roasting, which meets the standard of
ironmaking raw materials.
Iron and steel plant zinc-containing dust
Dispose of electric furnace dust (ZnO content 15-25%), zinc
volatilization rate >99%, dezincification iron can be directly
returned to the converter use.
Rare earth tailings regeneration
Extract magnetic iron from southern ionic rare earth mine tailings
(Fe₂O₃ content 20-30%), with rare earth loss rate controlled within 3%.
Fourth, the industry change driving force
Legislation in 32 countries requires metallurgical companies to
assume lifelong responsibility for solid waste treatment
Reconstruction of economic benefits
Treatment cost is 40%/ton lower than slag landfill
Each ton of recycled iron ore concentrate is 25% lower than the
price of imported iron ore
Carbon emission reduction target can generate additional
revenue of 18-22 RMB/tonne
Technology integration and innovation
5G+MEC edge computing realizes millisecond response in
roasting process
Digital twin system predicts magnetization reaction process
with 97% accuracy
Hydrogen-based gas technology reduces carbon footprint
of roasting by another 30