Technical background
Galvanizing is a kind of comparatively effectively and easily steel anti-corrosive method, and its coating has good sacrifice preservative activity; Hot dip alumin(i)um coating is fine and close, the durability period is long.And zinc aluminum alloy coating is used widely because of its performance that has had galvanic protection characteristic, the coating of durable protection feature and the zinc of aluminium concurrently will exceed quite a few times than superior performance, the antiseptic property of single-element coating than pure zinc coating.Because zinc-plated aluminium sheet; Have excellent comprehensive performance and beautiful appearance such as the Galvalume Coated Steel; The trend of alclad sheet and part steel plate galvanized has abroad appearred replacing with this coated sheet; Formed one zinc aluminum alloy coating heat, its product is mainly used in building industry, automotive industry, household electrical appliance and agricultural etc.
At present; A serious problem on the hot dip process production line is exactly the cadmia problem; Because zinc aluminum alloy coating aluminium content is higher, compares with the zinc pond of hot pure zinc plating, the composition in zinc pond changes a lot; Especially when elements such as adding silicon in the zinc-aluminium pond, with making facies relationship wherein become more complicated.Cadmia in zinc-aluminium zinc pond is mutually for containing the FeAl of zinc
L3With the Fe-Al-Si intermetallic compound.The density in density zinc-aluminium pond, zinc pond of comparing hot pure zinc plating is little, and 55%Al-Zn zinc-aluminium pond approximately is 1/2 of a hot pure zinc plating.Therefore, in the zinc-aluminium pond, will be easier to form suspension slag and end slag, the origin cause of formation of cadmia and influence factor are wanted much complicated in the specific heat pure zinc plating zinc pond.Typical zinc-plated aluminium Galvalume production line much all exists puzzlement people's cadmia problem at present; For example Australian Bluescope Steel has three Galvalume production lines to have serious cadmia problem, and equally also there is the cadmia problem in domestic many Galvalume production line.
Iron is the arch-criminal who causes cadmia; Source for iron in the zinc pond; Have research to think that they possibly come from the iron filings of surface of steel plate and be submerged in the hardware facility in the zinc pond, yet a large amount of plant produced experience, breadboard experiment and theoretical analysis show that all the dissolving of iron is the main source of iron in the zinc pond in the steel plate.Steel plate has just got into the moment in zinc pond, and steel plate and zinc pond are in the metastable equilibrium state, and this moment, steel plate and zinc pond iron level at the interface will be higher than the solubleness of iron in the zinc pond far away.Therefore, iron at the interface generates the part of alloy layer except participating in reaction, the remaining zinc pond that all got into.The generation of cadmia is because the iron level in the zinc pond has surpassed its saturation solubility in the zinc pond.Reduce the production of zinc pond cadmia; The content of iron is crucial in the control zinc pond; If can be, with the cadmia generation that reduces the zinc pond greatly, to improving zinc-plated aluminium quality product, enlarging the product application scope and have very important meaning through reducing the content of iron in the zinc pond someway.
Summary of the invention
The purpose of this invention is to provide a kind of method for removing iron in the continuous zinc coating production zinc-aluminium molten bath that is used for; Utilize the different solubility of iron under the differing temps and the density difference between iron content cadmia and the zinc-aluminium melt, make in the zinc-aluminium melt iron in stand at low temperature zinc pot, leave standstill cooling and separate out, generate the iron content cadmia and also be settled down to zinc-aluminium melt bottom; Can reduce to continuous and effective the solubleness of iron in the zinc pond; Thereby reduce the cadmia growing amount in the zinc pond, and then improve production efficiency and product quality, reduce production costs.
For achieving the above object, the present invention realizes through following technical scheme, comprises following steps:
The method of cooling deironing is left standstill in extracorporeal circulation in a kind of continuous hot-dipping zinc-aluminium; It is characterized in that: one stand at low temperature zinc pot is set on zinc-plated zinc pot next door; The stand at low temperature zinc pot temperature is lower than zinc-plated zinc pot temperature; Zinc-aluminium melt through driving zinc-plated zinc pot flow in the stand at low temperature zinc pot through the derivation pipeline between zinc-plated zinc pot bottom and the stand at low temperature zinc pot bottom; Utilize the different solubility of iron under stand at low temperature zinc pot and the zinc-plated zinc pot temperature and the density difference between iron content cadmia and the zinc-aluminium melt, make in the zinc-aluminium melt iron in stand at low temperature zinc pot, leave standstill cooling and separate out, generate the iron content cadmia and also be settled down to zinc-aluminium melt bottom; Separate out iron zinc-aluminium melt afterwards simultaneously and freely float, the zinc-aluminium melt of removing iron through stand at low temperature flows back to zinc-plated zinc pot naturally through the reflux line between stand at low temperature zinc pot top and the zinc-plated zinc pot top, accomplishes the purification to the galvanizing plating bath.
The method of cooling deironing is left standstill in extracorporeal circulation in above-mentioned a kind of continuous hot-dipping zinc-aluminium, it is characterized in that: said is 100-300kg/min through deriving the velocity of flow that pipeline flow into the zinc-aluminium melt in the stand at low temperature zinc pot.
The method of cooling deironing is left standstill in extracorporeal circulation in above-mentioned a kind of continuous hot-dipping zinc-aluminium, and it is characterized in that: stand at low temperature zinc kettle temperature is lower than 15~30 ℃ of zinc-plated zinc pot temperatures.
The method of cooling deironing is left standstill in extracorporeal circulation in above-mentioned a kind of continuous hot-dipping zinc-aluminium, it is characterized in that: 20~40% Fe has formed compound and has separated out in the zinc-aluminium melt.
The method of cooling deironing is left standstill in extracorporeal circulation in above-mentioned a kind of continuous hot-dipping zinc-aluminium, it is characterized in that: adopt the method for electromagnetic drive to make the zinc-aluminium melt of zinc-plated zinc pot flow in the stand at low temperature zinc pot.
The device of cooling deironing is left standstill in extracorporeal circulation in a kind of continuous hot-dipping zinc-aluminium; Comprise zinc-plated zinc pot; It is characterized in that: be provided with a stand at low temperature zinc pot on zinc-plated zinc pot next door; Be provided with the derivation pipeline between zinc-plated zinc pot bottom and the stand at low temperature zinc pot bottom; On the derivation pipeline, be provided with drive unit, be provided with reflux line between zinc-plated zinc pot top and the stand at low temperature zinc pot top, be used for the zinc-aluminium melt after the cooling deironing is back to zinc-plated zinc pot in order to the zinc-aluminium melt is exported to stand at low temperature zinc pot from zinc-plated zinc pot.
The device of cooling deironing is left standstill in extracorporeal circulation in above-mentioned a kind of continuous hot-dipping zinc-aluminium; It is characterized in that: the position of stand at low temperature zinc pot is higher than the position of zinc-plated zinc pot; Height difference H is 30~50cm, and the zinc-aluminium liquid level in the stand at low temperature zinc pot is higher than the zinc-aluminium liquid level in the zinc-plated zinc pot.
The device of cooling deironing is left standstill in extracorporeal circulation in above-mentioned a kind of continuous hot-dipping zinc-aluminium; It is characterized in that: said zinc-plated zinc pot adopts the electromagnetic induction heating mode to heat; Said stand at low temperature zinc pot adopts around resistive band heating carrying out heat tracing, reduces the zinc-aluminium melt is produced the sedimentation of separating out with the iron content cadmia of stirring and influence iron to accumulate.
The device of cooling deironing is left standstill in extracorporeal circulation in above-mentioned a kind of continuous hot-dipping zinc-aluminium; It is characterized in that: said derivation pipeline and said reflux line all adopt fire-resistant anti-corrosion graphite pipeline; Derive pipeline and reflux line and adopt circle or square structure, cross-section of pipeline is long-pending to be 3~15cm
2, the inlet water mean place of deriving the zinc-plated zinc pot of pipe connection is higher than and connects stand at low temperature zinc pot outlet level, and difference of altitude can flow into stand at low temperature zinc pot smoothly with the zinc-aluminium melt and be as the criterion; The inlet water mean place that reflux line connects stand at low temperature zinc pot is higher than the outlet level attitude that connects zinc-plated zinc pot, and difference of altitude can flow into zinc-plated zinc pot smoothly with the zinc-aluminium melt and be as the criterion.
The device of cooling deironing is left standstill in extracorporeal circulation in above-mentioned a kind of continuous hot-dipping zinc-aluminium, it is characterized in that: all adopt fire-resistant corrosion-resistant material with bottom inside around stand at low temperature zinc pot and the zinc-plated zinc pot, skin use steel plate layer.
The step and the characteristic of said method comprise:
(1) drive unit produces motivating force derives the zinc-aluminium melt from zinc-plated zinc pot, flow into stand at low temperature zinc pot through deriving pipeline; Stand at low temperature zinc pot is derived pipeline and is positioned at the lower position apart from the zinc the bottom of a pan all a little more than zinc-plated zinc pot; Lead to that the zinc melt flow rate is 100-300kg/min in the stand at low temperature zinc pan pipe road.
(2) stand at low temperature zinc pot adopts around the resistive band heating, reduces the flow velocity and the convection current of zinc melt in the stand at low temperature zinc pot; And rationally control is poor with zinc-plated zinc pot temperature, and the zinc melt temperature is lower than 15~30 ℃ of zinc-plated zinc pot temperatures in the stand at low temperature zinc pot.
(3) utilize the different solubility of iron under the differing temps and the density difference between iron content cadmia and the zinc-aluminium melt, make in the zinc-aluminium melt iron in stand at low temperature zinc pot, leave standstill cooling and separate out, generate the iron content cadmia and also be settled down to zinc-aluminium melt bottom; Separating out iron zinc-aluminium melt afterwards simultaneously freely floats.
(4) the zinc-aluminium melt through stand at low temperature removal iron flows back to zinc-plated zinc pot naturally through the reflux line that links to each other with zinc-plated zinc pot, and reflux line is positioned at zinc pot top, accomplishes the purification to the galvanizing plating bath; About 20~40% Fe has formed compound and has separated out in the zinc melt.
(5) in the continuous purification process, stand at low temperature zinc pot bottom iron content dregs continue to increase, and purify through online or time-out and remove stand at low temperature zinc pot bottom iron content dregs.
The method of cooling deironing is left standstill in extracorporeal circulation of the present invention, is the method that the continuous hot-dipping zinc-aluminium provides a kind of deironing to subtract slag, and iron removal is in the external completion of continuous zinc coating zinc pot.Under motivating force effects such as electromagnetic drive, make the zinc-aluminium melt-flow get into stand at low temperature zinc pot through deriving pipeline, during slowly rising, accomplishes the zinc-aluminium melt process of cooling deironing in stand at low temperature zinc pot; The iron of separating out generates the iron content cadmia and is settled down to zinc-aluminium melt bottom and removes, and flows back to zinc-plated zinc pot through the zinc-aluminium melt that stand at low temperature is removed iron naturally through the reflux line that links to each other with zinc-plated zinc pot, reduces zinc-aluminium melt dissolved ferric iron amount in the zinc-plated zinc pot; Fundamentally reducing the cadmia growing amount in zinc-aluminium pond; For producing high-quality hot dip process steel plate clean zinc pool environment is provided, reduces cadmia defective the hot-dip aluminum zinc steel plate, stablize the quality product of hot-dip galvanized steel sheet from the source; For being provided, high hot dip process steel plate quality gives security; Enlarge the product application scope, reduce the loss of zinc-aluminium, have considerable social benefit and economic benefit.
Description of drawings
The accompanying drawing of explanation is used for the present invention is done further explanation here, constitutes the application's a part, and indicative icon of the present invention is used to explain the present invention, does not constitute improper qualification of the present invention, and protection scope of the present invention is not limited to following synoptic diagram.
In the accompanying drawings:
Fig. 1 carries out steel plate galvanizing process synoptic diagram for the galvanizing pot.
Fig. 2 leaves standstill cooling deironing synoptic diagram for extracorporeal circulation of the present invention.
Fig. 3 leaves standstill the example approach synoptic diagram of cooling deironing for the extracorporeal circulation of continuous hot-dipping zinc-aluminium.
Wherein: [1] zinc-plated zinc pot, [2] zinc-plated zinc pot liquid level, [3] reflux line, [4] stand at low temperature zinc pot liquid level; [5] stand at low temperature zinc pot, [6] heating resistor band, [7] iron content cadmia deposition, [8] iron content cadmia; [9] zinc-aluminium melt, [10] drive unit, pipeline is derived in [11]; [12] band steel, roller is stablized in [13], [14] sinking roller.
Embodiment
Come specifically to introduce present embodiment below in conjunction with accompanying drawing and elaborate: present embodiment provided detailed embodiment and process, but protection scope of the present invention is not limited to following embodiment being to implement under the prerequisite with technical scheme of the present invention.
In conjunction with Fig. 1, Fig. 2 and shown in Figure 3, the method that the cooling deironing is left standstill in extracorporeal circulation in the continuous hot-dipping zinc-aluminium of the present invention comprises zinc-plated zinc pot 1 and stand at low temperature zinc pot 5.Stand at low temperature zinc pot 5 placement locations exceed zinc-plated zinc pot 1 and highly are H, and difference of altitude is 30~50cm.Steel plate galvanizing process is accomplished at zinc-plated zinc pot, and stand at low temperature zinc pot is used for leaving standstill the cooling deironing.Link to each other through derivation pipeline 11, reflux line 3 between zinc-plated zinc pot 1 and the stand at low temperature zinc pot 5, device has drive unit 10 in order to the zinc-aluminium melt is exported to stand at low temperature zinc pot from zinc-plated zinc pot on derivation pipeline 11.
Said zinc-plated zinc pot 1 adopts the electromagnetic induction heating mode to heat; Stand at low temperature zinc pot 5 adopts around resistive band 6 heating it is carried out heat tracing, and adopting purpose around resistive band 6 heating is to prevent that type of heating such as electromagnetic induction from producing the sedimentation of separating out with the iron content cadmia of stirring and influence iron to the zinc-aluminium melt and accumulating.
The zinc-aluminium melt flows into stand at low temperature zinc aluminum pot 5 bottoms via deriving pipeline 11 under the driving of drive unit 10, zinc-aluminium melt 9 slowly rises in stand at low temperature zinc pot 5.Through temperature control around resistive band 6; Make stand at low temperature zinc pot 5 interior zinc melt temperatures be lower than 15~30 ℃ of zinc-plated zinc pot 1 temperature; Because the reduction of temperature makes the solubleness of iron in zinc-aluminium melt 9 reduce; Separate out thereby make in the zinc-aluminium melt 9 of iron from rise, generate iron content cadmia 8 and grow up and progressively be settled down to stand at low temperature zinc pot 5 bottoms and form iron content cadmia deposition 7.Zinc-aluminium melt 9 through the cooling deironing after be back to zinc-plated zinc pot 1 by reflux line 3.Zinc-aluminium is carried out circulation deferrization, and about 20~40% Fe has formed iron containing compounds and has separated out in the zinc melt.
Visible from above-mentioned embodiment, the method that the cooling deironing is left standstill in continuous hot-dipping zinc-aluminium of the present invention extracorporeal circulation has to utilize and leaving standstill cooling and analyse the method for iron, effectively removes the iron in the zinc-aluminium melt; Reduce the growing amount of cadmia through the iron level in the reduction zinc-aluminium melt; For producing high-quality hot dip process steel plate clean zinc pool environment is provided, fundamentally avoids cadmia generation of defects in the hot-dip aluminum zinc steel plate, stablize the quality product of hot-dip galvanized steel sheet; For being provided, high hot dip process steel plate quality gives security; Enlarge the product application scope, can reduce the loss of zinc-aluminium simultaneously, bring considerable social benefit and economic benefit.