Scraper/pickaxe scraping: use high-temperature-resistant tools (e.g. graphite scraper) to scrape away the floating slag on the surface of zinc solution and the deposited zinc slag at the bottom, applicable to zinc slag thickness ≤ 150mm.
Author: Anna
I. Daily cleaning methods and frequency
Mechanical cleaning
Scraper/pickaxe scraping: use high-temperature-resistant tools (e.g. graphite scraper) to scrape away the floating slag on the surface of zinc solution and the deposited zinc slag at the bottom, applicable to zinc slag thickness ≤ 150mm.
Vibration / loosening method: through the vibration of the zinc pot or control the supply of oxygen to make the zinc dross loose, easy to centralized removal, suitable for small-scale zinc dross treatment.
Physical and chemical treatment
Aluminum replacement method: add 0.01~0.02% pure aluminum to the zinc liquid, prompting the formation of iron in the zinc slag slag floating slag (ferro-aluminum alloy), to enhance the efficiency of slagging and reduce the bottom of the deposition.
Acid washing method: After stopping the furnace, use hydrochloric acid to soak the zinc slag (e.g. zinc chloride solution) to dissolve the residual metal, need to pay attention to the corrosion risk of the acid on the pot body.
Furnace Nose and Liquid Level Maintenance
Specialized Slag Scoop Cleaning: Clean the floating slag in the furnace nose 2~3 times per shift to prevent zinc dust from entering the plating layer with the strip steel.
Zinc liquid surface coverage: keep the liquid surface higher than the heating surface to avoid the formation of zinc ash in the high-temperature oxidation zone, and skim off the surface dross in time.
II. Temperature and zinc composition control
Precise temperature management
The temperature of zinc liquid is controlled at 430~450℃ or 540~600℃, avoiding the “peak iron loss area” of 480~510℃ and reducing the generation of zinc slag. The temperature of the strip should be lower than the temperature of the zinc.
The temperature of the strip into the pot should be lower than the liquid zinc temperature within 20℃, to prevent the temperature difference from aggravating the formation of zinc slag.
Zinc liquid composition optimization
Aluminum content control: 0.19~0.22% for normal galvanizing, 0.10~0.15% for alloying galvanizing, to balance liquidity and zinc dross suppression.
Iron content monitoring: through the fluxing agent regeneration and anti-corrosion welding materials to reduce the iron ion carryover, the iron content in the zinc liquid needs to <0.05%.
III. Furnace shutdown for maintenance and in-depth maintenance
Periodic furnace shutdown operation
Furnace shutdown for maintenance every 12 months, thoroughly remove the bottom zinc slag, repair the corroded parts of the zinc pots, and pumping zinc or pre-expansion treatment is required when the furnace is shut down.
After furnace shutdown, the zinc is recovered by vacuum distillation or fusion separation (550~580°C static precipitation), and the residual iron powder is handled separately.
Equipment and process upgrading
Intelligent control system is introduced to monitor the zinc liquid temperature, composition and air knife parameters in real time to reduce the error of manual intervention.
Adoption of closed-loop regeneration technology to reduce the adhesion of zinc dust and improve the uniformity of plating layer.
Regular cleaning of zinc slag and ash should be combined with daily mechanical cleaning (scraping, slagging), zinc composition and temperature control (aluminum addition, temperature control to avoid peaks), as well as in-depth maintenance during furnace shutdowns (zinc pumping maintenance, process upgrades). (zinc pumping overhaul, process upgrading). Through standardized operation and technological innovations (e.g. aluminum replacement, intelligent monitoring), zinc consumption can be significantly reduced and pot life extended.