Energy-Saving Waelz Process Kiln, 1200° C Working Temp, for Non-Ferrous Metal Recycling

• Customization: Available
• Production Scope: Product Line
• Condition: New
• Model NO.: 4.2*75m
• Automation: Automatic
• After-sales Service: Engineers Available to Service Machinery Overseas
• Transport Package: Frame Work
• Specification: 6.5*77m
• Trademark: Bullis
• Origin: Shangdong
• HS Code: 8501109101
• Production Capacity: 500sets/Month

Product Description

The application of metallic zinc is becoming increasingly widespread. Zinc is commonly used as a surface coating for steel products. A large amount of statistical data indicates that the proportion of galvanized scrap steel in EAF raw materials is growing. Consequently, the zinc content in EAF dust is also increasing.
The core of Waelz technology is the reduction of metal oxides such as zinc, lead, and cadmium in a rotary kiln using coke. This technology was initially used for extracting zinc from low-grade zinc ore and later applied to recover metallic zinc from zinc slag. Over the past 30 years, it has been successfully used for electric arc furnace (EAF) dust treatment. Waelz technology can be utilized in both the steel and zinc smelting industries.

Advantages of Recovering EAF Dust Using Waelz Technology

1. Mature and Reliable Technology - Waelz technology has been widely applied in industrial production, making it a well-established and reliable process.
2. Simple Equipment Installation - The installation process is straightforward and does not require complex infrastructure.
3. Outstanding Economic Benefits - The recovered zinc oxide can be used in all zinc smelting plants, while the slag generated after smelting can be utilized for road construction.
4. Environmental Compliance - Industrial production using Waelz technology ensures that exhaust emissions fully comply with European environmental protection standards.
5. Operational Flexibility - By modifying the process, various types of dust can be treated efficiently.
6. Low Energy Consumption - The coke consumption required to process 1 ton of EAF dust is less than 200 kg.

Other EAF dust recycling processes are still in the research or semi-industrial experimental stages, often involving high production costs. These include smelting cyclone separators, shaft furnaces, plasma heating furnaces, and electric heating furnaces. While these alternative processes are not suitable for EAF dust treatment, they are applicable for stainless steel and AOD (Argon Oxygen Decarburization) dust treatment.
In summary, the Waelz kiln is a key technology for recovering zinc from EAF dust. By using heat and carbon to reduce zinc oxide to zinc metal, the kiln produces valuable zinc oxide and creates environmentally friendly byproducts like slag.

Key Features of the Waelz Kiln:

• Rotary Kiln Design: The kiln rotates to ensure uniform mixing and heating of the raw materials. The rotation is typically at 1 revolution per minute.
• Temperature Control: The process is carried out at high temperatures (up to 1200°C) to drive the reduction reactions effectively.
• Gas and Dust Management: The kiln has an exhaust gas system that treats harmful emissions and meets strict environmental regulations.
• By products: The main byproducts are zinc oxide (which can be further processed) and slag (which can be used in road construction)
• Basic Working Principle of the Waelz Kiln:
• Raw Material Preparation:
• 1. Before entering the kiln, EAF dust, coke (a carbon-based reducing agent), and fluxing agents like limestone (or other slag-forming materials) are mixed together. In some cases, self-reducing pellets (SRP) are created by mixing the EAF dust with coke and lime.
  2. This mixture is homogenized and prepared to be fed into the kiln.
• Feeding into the Kiln:
• 1. The prepared raw materials are fed into the Waelz rotary kiln through a feed inlet.
  2. The kiln rotates slowly (typically one revolution per minute) to ensure the materials are thoroughly mixed and exposed to heat evenly.
• Heating and Reduction:
• 1. The kiln operates at a high temperature (up to 1200°C or more).
  2. The incoming feed undergoes drying first, followed by heating.
  3. At high temperatures, carbon monoxide (CO), produced by the coke, reduces the zinc oxide (ZnO) in the dust to zinc metal (Zn). This is a reduction reaction, where the zinc oxide is reduced by the carbon in coke.
  4. The reduction reaction is endothermic, meaning it absorbs heat. The heat required for the reaction is largely supplied by the oxidation of carbon monoxide (CO) from the coke, which generates additional heat.
• Chemical Reactions:
• 1. In the Waelz kiln, zinc oxide is reduced to zinc metal, while other impurities form slag.
  2. The chemical reaction can be simplified as follows: ZnO+CO→Zn+CO2ZnO + CO \rightarrow Zn + CO_2ZnO+CO→Zn+CO2
  3. The zinc metal sinks to the bottom, while other impurities form slag, which floats above the zinc.
• Formation of Slag and Zinc Oxide:
• 1. The slag, made up of unwanted materials (e.g., calcium oxide, silicon dioxide), is separated from the zinc metal during the process.
  2. The resulting zinc oxide produced from the reaction can be further processed and sold to zinc smelting plants or other chemical industries. The zinc content in this oxide is typically 54%-60%.
• Cooling and Collection:
• 1. As the zinc oxide and slag leave the kiln, they are cooled, and the slag is separated from the zinc product.
  2. The zinc oxide can then be sold, while the slag is generally used for road construction or other industrial purposes.

Main Technical Specifications

Model	Diameter/m	Length/m	Slope/%	Capacity(t/d)	Rotating Speed	Motor Powder/kw
Φ2.5x40m	2.5	40	3.6	180	0.44-2.44	55
Φ2.5x50m	2.5	50	3.0	200	0.62-1.86	55
Φ2.5x54m	2.5	54	3.5	280	0.48-1.45	55
Φ2.7x42m	2.7	42	3.5	320	0.10-1.52	55
Φ2.8x44m	2.8	44	3.5	450	0.437-2.18	55
Φ3.0x45m	3.0	45	3.5	500	0.5-2.47	75
Φ3.0x48m	3.0	48	3.5	700	0.6-3.48	100
Φ3.0x60m	3.0	60	3.5	800	0.3-2.0	100
Φ3.2x50m	3.5	50	4.0	1000	0.6-3.0	125
Φ3.3x52m	3.3	52	3.5	1300	0.266-2.66	125
Φ3.5x54m	3.5	54	3.5	1500	0.55-3.4	220
Φ3.6x70m	3.6	70	3.5	1800	0.25-1.25	125
Φ4.0x56m	4.0	56	4.0	2300	0.41-4.07	315
Φ4.0x60m	4.0	60	3.5	2500	0.396-3.96	315
Φ4.2x60m	4.2	60	4.0	2750	0.41-4.07	375
Φ4.3x60m	4.3	60	3.5	3200	0.396-3.96	375
Φ4.5x66m	4.5	66	3.5	4000	0.41-4.1	560
Φ4.7x74m	4.7	74	4.0	4500	0.35-4.0	630
Φ4.8x74m	4.8	74	4.0	5000	0.396-3.96	630
Φ5.0x74m	5.0	74	4.0	6000	0.35-4.0	710
Φ5.6x87m	5.6	87	4.0	8000	Max 4.23	800
Φ6.0x95m	6.0	95	4.0	10000	Max 5.0	950*2