In the field of non-ferrous metal smelting, the treatment of zinc materials has always been one
of the technical difficulties. Especially the crude zinc oxide materials containing high fluorine
and chlorine elements, whose complex chemical properties pose a serious challenge to the
traditional process. In recent years, multi-chamber furnace technology, with its unique structural
design and process advantages, has emerged in the field of zinc fume fluorine and chlorine removal,
and has become a key technological breakthrough to improve resource utilization and reduce
environmental risks.
Principle of multi-chamber furnace technology and fluorine and chlorine
removal mechanism
As a typical multi-layer counter-current reaction equipment, the multi-chamber furnace constructs a gradient heat
treatment environment through a layered temperature control system. When the zinc fume containing chlorofluorine
(such as lead chloride, lead fluoride, zinc chloride, zinc fluoride and other compounds) enters the furnace body, the
physicochemical transformation occurs within the precise temperature control interval of 600-750℃. The micro-negative
pressure environment maintained in the furnace not only accelerates the gasification and escape of chlorofluorocarbons,
but more importantly, realizes the efficient separation of gas-phase products and solid residues through pressure regulation.
Compared with single-stage high-temperature treatment equipment, the multi-chamber furnace's tiered structure
creates a unique “step-by-step activation” effect: the lower high-temperature zone is responsible for decomposing
the more stable chlorofluorocarbons, the middle transition zone carries out the gas-solid separation, and the upper
low-temperature zone effectively inhibits the secondary volatilization of valuable metals such as zinc. This gradient
processing mode makes the removal efficiency of fluorine and chlorine elements increase to more than 95%,
and at the same time, the recovery loss of zinc metal is controlled within 0.5%.
Technological breakthrough compared with the traditional process
There are obvious limitations in the treatment of high chlorofluorine zinc materials in the traditional Wiltshire kiln:
although the working temperature of over 1300℃ can realize the removal of chlorofluorine, it brings problems
such as a large amount of volatilization of zinc metal (the loss rate of more than 3%), high energy consumption
(the thermal efficiency is less than 40%), and doubling of the flue gas treatment load. The multi-chamber furnace
realizes process upgrading through three major technological innovations:
Low-temperature and high-efficiency reaction system: Reducing the processing temperature to below 750°C, and
completing the fluorine and chlorine removal under mild conditions by prolonging the material residence time
(up to 4-6 hours) and strengthening the mass transfer efficiency. Comparative data shows that the energy cost can
be reduced by about 35%.
Self-purifying flue gas channel: The specially designed deflector system fully separates gaseous chlorofluorocarbons
(e.g., HF, HCl) from the carry-over soot, reducing the load on the back-end dedusting system by 40%, and reducing
the investment in supporting environmental protection facilities by 20%.
Optimization of metal recovery rate: the direct recovery rate of zinc metal is increased to more than 99.2%, and the
enrichment of lead, silver and other rare precious metals in the by-products is increased by 2-3 times, which
significantly enhances the comprehensive utilization value of resources.
Economic and environmental double value of process advantages
From the point of view of production practice, the use of multi-chamber furnace technology to deal with each ton
of high-fluorine zinc chloride material can produce multi-dimensional benefits:
Environmental benefits: flue gas emissions are reduced by 60%, and the concentration of fluorine and chlorine
pollutants is stably lower than 50mg/Nm³, which fully meets the GB25466-2010 emission standards;
Economic benefits: zinc metal recovery value-added up to 1200 yuan/ton, auxiliary material consumption reduced
by 25%, equipment maintenance cycle extended to 18 months;
Process compatibility: it can handle complex materials with fluorine and chlorine content up to 8%, strong
adaptability to raw material fluctuation, and 70% reduction of system start-stop energy loss.
Especially in the context of the “double carbon” strategy, the comprehensive energy consumption per unit of
product (standard coal) down to 0.28 tons, compared with the traditional process of carbon emission reduction
of up to 45%, for smelting enterprises to build a green production system provides a key technical support.
Innovative direction of industry application
With the integration and application of intelligent control technology, the modern multi-chamber furnace is upgrading
in the direction of intelligence: real-time monitoring of the temperature, pressure and material distribution status of
each bed through the DCS system, combined with the AI algorithm to dynamically optimize the heat supply curve and
feed rate, the fluctuation range of the fluorine and chlorine removal efficiency is narrowed from ±5% to ±1.5%. Some
advanced systems have been realized:
The waste heat recovery device reduces the flue gas temperature from 650℃ to 150℃ in a stepwise manner, and the
heat recovery efficiency breaks through 85%;
The modularized design reduces the equipment footprint by 30%, and the capacity elasticity adjustment range
reaches 50-120%;
The automated ash cleaning system reduces the frequency of manual intervention from twice a day to once a week.
In the field of zinc secondary resource recovery, the technology has particularly prominent advantages in the treatment
of materials such as fluorochlorine-containing waste catalysts and electric arc furnace soot. Data from a demonstration
project shows that when treating complex zinc soot containing 3.5% chlorine and 2.1% fluorine, the residual fluorine
and chlorine in the final residue is stabilized at less than 0.3%, and the purity of zinc ingots reaches 99.995%, with
the technical indexes reaching the international advanced level.
Technology outlook and development trend
With the increasingly strict environmental regulations and the continuous decline of resource grade, the multi-chamber
furnace technology is extending from the zinc smelting field to the lead, copper and other metal recycling scenarios.
The new generation of technology R&D is focused on:
Developing special alloy grates that are resistant to fluorine and chlorine corrosion, extending the service life of
core components to more than 5 years;
Integrating microwave-assisted heating technology to further reduce reaction activation energy;
Constructing a fluorine and chlorine resource recovery system, and upgrading the purity of by-product hydrofluoric
acid and hydrochloric acid to industrial-grade standards.
It is foreseeable that this technological innovation, which started with zinc fume treatment, is reshaping the clean
production paradigm of non-ferrous metal smelting. Its core value not only lies in solving the problem of fluorine
and chlorine pollution, but more importantly, it opens up a new path for the efficient utilization of complex secondary
resources, and provides a strong technical fulcrum for the development of circular economy. Nowadays, when green
development has become a global consensus, this kind of technological innovation, which is both economical and
environmentally friendly, will surely lead the metallurgical industry to a more sustainable future.