Background technology
The vanadium of 80%-90% is used for Iron And Steel Industry, and its major cause is that the same carbon of vanadium, nitrogen reaction form infusible carbon, nitride, and these compounds can play precipitation hardening and grain refining in steel.Therefore, the VN alloy of vanadium carbide, vanadium nitride composition plays a part increasingly important in containing vanadium steel production.VN alloy can be used in structure iron, tool steel, pipe line steel, reinforcing bar, common engineering steel and the cast iron.Existing studies show that: VN alloy makes an addition to wear resistance, erosion resistance, toughness, intensity, ductility and the comprehensive mechanical performances such as hardness and thermal fatigue resistance that can improve steel in the steel, and make steel have good weldability energy, and can play effects such as eliminating the inclusion extension.In Hi-Stren steel, directly add VN alloy and compared following advantage: more effectively play precipitation strength and crystal grain thinning than vanadium iron with using vanadium iron; Reduce adding cost~40% of vanadium; Help the comprehensive utilization of vanadium and nitrogen, significantly improve the comprehensive mechanical performance of steel.VN alloy reinforcement ratio regular reinforcement consumption reduces about 14%.VN alloyization is widely used in non-hardened and tempered steel and CSP high-intensity band steel, and VN alloyization combines with TMCP technology and is applied in the production of China high strength H shaped steel.
The production technology of existing production VN alloy mainly contains following several:
At first, U.S. Pat 3334992 and US4040814, the vanadium nitrogen alloy preparation method that Wang Gonghou, P.K.Tripathy, C.Buker etc. disclose and study.It is characterized in that: adopt V
2O
3With carbonaceous reducing agent be raw material, in high-temperature vacuum equipment, prepare vanadium carbide, vanadium carbide makes VN alloy through nitriding again.China's Panzhihua Iron also adopts this method at present.These methods have the following disadvantages: (a) Production Flow Chart is a two-step approach, promptly discontinuous formula production method.The Production Flow Chart of single-pot in this single stove formula or the tunnel furnace, production efficiency is low, and product composition is inhomogeneous; (b) carbothermic reduction reaction carries out in the high-temperature vacuum device, and equipment cost and operating cost are than higher.
Secondly, Chinese patent CN1562770 and CN1644510 disclose the synthetic vanadium nitride of microwave.This method has the following disadvantages: (a) owing to microwave penetration power limited (being generally less than 5cm), stove causes the heating meeting inhomogeneous too greatly; (b) and the power of single microwave tube limited, easily mutually heating again causes the microwave tube life-span low between a plurality of microwave tubes, thermo-efficiency also can reduce; (c) in the preparation process of vanadium nitride, owing to going deep into of reducing degree, reaction product has the character of metal more, and this reflection to microwave also can be more and more stronger, causes the finished product reduction insufficient, and the residual oxygen of product is higher.
In a word, disclosed about vanadium nitrogen alloy preparation method both at home and abroad at present, aggregate analysis has following characteristics: (a) technical process all is that carbothermic reduction and nitriding processing are separately carried out, be discontinuousization production, wherein carbothermic reduction is divided into prereduction again and reduces two steps eventually, like this production cycle longer, reaction time is basically all at 5~8 hours, even longer; (b) on the type of heating, what generally adopt is the type of heating that resistive heating and induction heating combine, and resistance heating device conducts heat slow, and thermal losses is big, and the power consumption cost of product is higher; (c) selected raw materials cost height, the material composition proportioning is indeterminate.
Summary of the invention
The object of the present invention is to provide a kind of method and apparatus of production VN alloy, realized that raw materials cost is low, facility investment is few, the production efficiency height, and product composition is stable, energy-conserving and environment-protective.
To achieve these goals, technology of the present invention comprises: select materials, batching, batch mixing, pressure ball, green-ball oven dry, go into the stove reaction; It is characterized in that: vanadium pentoxide powder, carbon dust, brown iron oxide and binding agent are mixed back compacting balling-up by a certain percentage, the ball of compacting is packed in the Medium frequency induction shaft furnace, under nitrogen atmosphere, under 1000~1700 ℃ of temperature, react and came out of the stove in 2~3 hours, then cooling obtains V:76~81%, N:12~20%, C:1~6%, Fe:1~2% under nitrogen atmosphere, and apparent density is not less than 3.5kg/cm
3Vanadium-nitrogen alloy product.The concrete operations step is as follows:
Select materials: V
2O
5Directly select commercially pure vanadium pentoxide powder for use, granularity is less than 0.25 millimeter; Carbon dust is industrial carbon dust, and granularity is less than 0.25 millimeter; Brown iron oxide can directly be selected industrial Powdered ferric oxide for use, and granularity is less than 0.25 millimeter; Used binding agent is a polyvinyl alcohol water solution.
Batching: carbon dust weight is V
2O
525~36% of weight, the weight of brown iron oxide are V
2O
53~5% of weight, weight of binder are V
2O
56~10% of weight.
Batch mixing: weighing V according to the above ratio
2O
5, carbon dust, brown iron oxide, the mixer of packing into mixed 20~30 minutes, then evenly added binding agent, mixed 20~30 minutes again, made the abundant mixing of raw material.
Pressure ball: the raw material of mixing is pressed into green-ball through ball press, and the ball of compacting is oblate spheroid shape, peach-pit shape or other bulk, is of a size of length 20~50mm, width 20~50mm, thickness 15~25mm.
The green-ball oven dry: the green-ball that suppresses advances the stoving oven oven dry, and bake out temperature is controlled at 150~250 ℃ scope, dries 1~3 hour.
Go into stove reaction: with the pellet of the oven dry graphite charging tray of packing into, charge graphite charging tray is gone into stove from induction shaft furnace top inlet continuously with the speed of 10~15min/ dish.Stove internal induction district temperature range is controlled between 1000~1700 ℃, logical nitrogen protection in the stove.According to the analytical calculation and the test result analysis of theory, Vanadium Pentoxide in FLAKES and carbon finally can be thought under nitrogen atmosphere following the reaction taken place:
V
2O
5+(2y+5)C+xN
2=2VN
xC
y+5CO
In the reaction later stage, because the minimizing of raw material C content, some participates in secondary reduction reaction generation CO the CO gas of generation
2It is as follows that raw material is gone into the stove reaction principle:
(1) temperature is selected: calculation of thermodynamics shows that when temperature reaches 762 ℃ more than reaction can take place, and considers the influence of kinetic factor, and on theory and the basis to interpretation, we select temperature range is 1000~1700 ℃.
(2) temperature control measure: according to the heating principle of induction shaft furnace, induced current power is high more, and outlet temperature is high more in the stove, so according to the temperature that records with the thermometric galvanic couple, regulate temperature in the stove by regulating induced current power, make within its temperature range that is stabilized in requirement.Because nitrogenizing reaction is thermopositive reaction, when ordinary production, along with constantly carrying out of reaction, reaction heat can substitute a part of induction heat, and can turn down induced power this moment, and is too high with what avoid furnace temperature to rise, and equipment is caused damage.So also can make full use of reaction heat effect, reduce power consumption.
(3) heating principle: the production unit that the present invention adopts is the Medium frequency induction shaft furnace, because the electroconductibility of raw material green-ball is very weak and magnetic property is poor, is difficult for sensed heating, so select for use the graphite cannula inwall as main induction heating element; The charge charging tray is the graphite charging tray, and each the graphite charging tray in the stove internal induction district itself can sensedly generate heat, and is less important heating element; And graphite charging tray thermal conductivity is better, helps the thermal conduction of storeroom in the stove, so that the relative equilibrium of the interior temperature of stove.
(4) walk the material mode: the charge charging tray is gone into stove from induction shaft furnace top, come out of the stove in the bottom, and nitrogen feeds from the induction furnace bottom, and the graphite material tray bottom has breather hole, and the gas of being convenient to nitrogen and generation is up.Because the device bottom sealing, sealing baffle is opened automatically when discharging, and air-leg is pushed into blow tank to induction furnace bottom charging tray, and then sealing baffle is from dynamic seal, and the gas of nitrogen and generation can only be overflowed from the induction furnace top like this.Thisly walk to expect that the characteristics of mode are exactly that waste heat makes full use of, reduce thermosteresis.The charge charging tray of process induction zone can make the nitrogen temperature that enters induction zone reach about 800 ℃ at the nitrogen that preheating bottom in cooling zone feeds, and reduces the influence of nitrogen to furnace temperature; The gas that generates through the residue nitrogen of induction zone and reaction is because temperature is higher, and the charge charging tray can the preheating top when the top inlet is overflowed is elevated to about 800 ℃ charge charging tray temperature when advancing as induction zone.
(5) walk material speed: step-down gear and elevator by induction shaft furnace bottom are adjusted the downstream rate of charge charging tray in stove, according to Theoretical Calculation result and commercial test results, the stove speed of going into of charge graphite charging tray is 6~10min/ dish, and charging tray is controlled at by the induction shaft furnace time and was advisable in 2~3 hours; Nitrogen flow is controlled at 10~40m
3/ hour.
Production sampling test and finishing packing: the charge charging tray enters blow tank, the sampling analysis product composition, and going out according to assay proves, product enters the finishing packing shop after fully cooling off under nitrogen atmosphere in blow tank.
The device that single stage method of the present invention for achieving the above object prepares VN alloy continuously comprises that this device comprises Vanadium Pentoxide in FLAKES powder storehouse, powdered carbon storehouse, brown iron oxide storehouse, adhesive receptacle, mixer, ball press, dryer, watch-keeping cubicle, Medium frequency induction shaft furnace, nitrogen-making device, graphite charging tray and blow tank; Change the top that two vanadium powder storehouses, powdered carbon storehouse, brown iron oxide storehouse, adhesive receptacle are fixed on weighing instrument, link to each other with mixer, ball press with handling apparatus, be connected mutually with induction furnace by handling apparatus in turn by the belt transmission; Vanadium Pentoxide in FLAKES powder storehouse, powdered carbon storehouse, brown iron oxide storehouse, adhesive receptacle are fitted with weighing instrument and operated pneumatic valve respectively, and weighing instrument, operated pneumatic valve link to each other with the watch-keeping cubicle.
Medium frequency induction shaft furnace of the present invention is made up of induction zone I, cooling zone II, gripping unit III, drawing mechanism VI and lifting device V; Medium frequency induction shaft furnace induction zone I is followed successively by graphite cannula inwall, thermal insulation layer, thermometric galvanic couple and induction coil from inside to outside, and thermometric galvanic couple, induction coil link to each other with the watch-keeping cubicle; Graphite cannula inwall and water jacket that cooling zone II is followed successively by from inside to outside; Drawing mechanism VI comprises air-leg, and air-leg links to each other with the watch-keeping cubicle; Lifting device V comprises pallet, support bar, elevator, variable-speed motor.
Medium frequency induction shaft furnace induction heating element is graphite charging tray and graphite cannula inwall, and main heating element is the graphite cannula inwall, and temperature is 1000~1700 ℃ in the stove, by the online temperature control in watch-keeping cubicle; Speed with 10~15min/ dish adds, exports from induction shaft furnace bottom charge graphite charging tray continuously from induction shaft furnace top; Nitrogen feeds from induction shaft furnace bottom, and nitrogen flow is 10~40m
3/ h; It is 2~3h that the charge charging tray promptly reduces the nitriding reaction times shaft furnace time by induction, obtains V:76~81%, N:12~20%, C:1~6%, Fe:1~2%, and apparent density is not less than 3.5kg/cm
3Vanadium-nitrogen alloy product.
Compare with the method and apparatus of other production VN alloy, the present invention has following advantage:
1, technical process is " single stage method " about the continuous production VN alloy in the present invention.So-called " single stage method " promptly studies have shown that reduction nitriding reaction takes place in 1000~1700 ℃ of temperature ranges simultaneously, and raw material obtains qualified vanadium-nitrogen alloy product through the induction shaft furnace is disposable, and is with short production cycle, the production efficiency height.Existing other technology and equipment all is a two-step approach, be a kind of Vanadium Pentoxide in FLAKES reduction be divided into prereduction and eventually two steps of reduction, another kind of flow process is divided into vacuum reducing and two steps of nitriding, two kinds of flow process complexity, the production cycle is long, production efficiency is low, facility investment is big.
2, production equipment less investment of the present invention, the thermo-efficiency height.Based on " single stage method " production technique, main production equipments of the present invention is established one section induction coil for the induction shaft furnace, and responding to main heating element is graphite cannula inwall and graphite charging tray, and inferior heating element is a pellet; Because the oilness of graphite, the charge charging tray is descending unobstructed in stove, helps serialization production; The graphite charging tray is also avoided the erosion of pellet to the furnace wall, and thermal conduction is fast, uniformity of temperature profile in the stove, and the thermo-efficiency height helps producing the uniform vanadium nitrogen of composition product; Existing other technology, adopt the induction shaft furnace to produce, induction furnace generally is divided into prereduction section and reduction nitriding section, takes different type of heating for two sections, the employing resistive heating that the prereduction section has, the work-ing life of resistance wire is limited, adopt induction heating owing to do not adopt graphite charging tray thermal conduction poor, what have is heating element with the raw material directly, overall like this thermo-efficiency is all low than the present invention, facility investment is big, and control is complicated; The employing tunnel furnace and the pushed bat kiln that have are different from the present invention, and these two kinds of investment of production equipment are big, and are not easy to serialization production.
3, the technological process of production of the present invention and device can be realized temperature online control.Temperature is the key factor of producing qualified vanadium-nitrogen alloy product, production unit of the present invention is characterized in that responding to the shaft furnace induction zone temperature thermocouple is housed, can detect and regulate temperature in the stove in real time, stablize, be convenient to the vanadium nitrogen product of production stable components by regulating the current setting furnace temperature.And by induction furnace bottom charging tray to the preheating of nitrogen and top gas to the heating of charge charging tray, help heat energy recycle.Existing other technology does not all have online temperature detection, because the uncontrollable instability that causes product composition of temperature of reaction; And well do not accomplish the preheating efficient recovery.
4, the raw materials for production of the present invention's employing are Vanadium Pentoxide in FLAKES, carbon dust and ferric oxide, are the primary raw materials that is easy to get all, and raw materials cost is low; The brown iron oxide that the present invention selects for use has promoter action to reduction nitriding reaction, and can shrink finished product pellet volume, makes the pellet densification.Existing other technology is selected vanadous oxide and iron powder for use, and raw materials cost is higher.
Embodiment
Embodiment
According to process program of the present invention, carried out produced in series enforcement at production equipment of the present invention.Selected raw material is respectively: contain V
2O
5Be 98.2% vanadium pentoxide powder, C content is 99.3% carbon dust, Fe
2O
3Content is 90% brown iron oxide, contains the polyvinyl alcohol water solution binding agent of polyvinyl alcohol 10%.Concrete implementation step as previously mentioned, implementation condition parameter such as table 1, result of implementation such as table 2.
Table 1. is implemented working condition and parameter
Annotate
*: the furnace wall thermopair records temperature and is lower than temperature in the stove, and the temperature difference is about 100 ℃
Table 2. is implemented the product result
The concrete operations flow process is as follows:
At first, match raw material in the ratio of processing requirement.Adorn Vanadium Pentoxide in FLAKES powder storehouse 1, powdered carbon storehouse 2, brown iron oxide storehouse 3 respectively producing required vanadium pentoxide powder, carbon dust, brown iron oxide, the binding agent container 4 of packing into, open Vanadium Pentoxide in FLAKES powder storehouse 1, powdered carbon storehouse 2, brown iron oxide storehouse 3 lower part outlet place operated pneumatic valve 6 automatic blankings to mixer 7, by the weighing instrument 5 metering cutting stock weights equipped with each feed bin.Weighing instrument 5 links to each other with watch-keeping cubicle 10 with operated pneumatic valve 6, can carry out remote auto control.When weighing instrument 5 shows that cutting stock weight reaches the weight of batching requirement, close the operated pneumatic valve 6 of feed bin feed opening, open mixer 7, stirring and evenly mixing 30 minutes, then open adhesive receptacle 4 bottom operated pneumatic valves 6 and in mixer 7, add the binding agent that requires, restir mixing 30 minutes.The raw material of mixing is sent to ball press 8 compacting balling-up through conveyor, and the raw material green-ball is through being sent to dryer 9 oven dry 1~3 hour through belt.
Secondly, with the pellet of the oven dry graphite charging tray 13 of packing into, charge graphite charging tray 13 winches to induction shaft furnace 11 top filling platforms through hanging apparatus.The nitrogen that nitrogen-making device 12 is produced is fed in the stove by induction shaft furnace bottom, guarantees that in the stove be the pressure-fired environment, makes nitrogen can overcome resistance between charging tray and up smoothly.Synergetic charge charging tray is supported by the pallet 19 of bottom band support bar 21 in the induction furnace, and support bar 21 links to each other with elevator 22, can oscilaltion, regulate rising or falling speed by variable-speed motor 23.Charge graphite charging tray in the stove descends continuously with given pace, and each charge graphite charging tray is certain through the time of induction zone like this, has guaranteed the stability of product composition.When pallet 19 is reduced to low spot, be that bearing surface is when equal with the blow tank bottom surface, gripping unit III clamps graphite charging tray 10 in the stove fast, air-leg 20 is pushed into blow tank fast to bottom graphite charging tray, and pallet 19 fast rise then are when bearing surface contacts with top graphite charging tray, gripping unit III unclamps, pallet 19 supports graphite charging tray continuation decline in the stove, circulates with this, realizes serialization production.Wherein, at the production initial stage, because the chemical heat effect is low, need higher induced current power could guarantee the production temperature of reaction that stove is interior, along with proceeding of producing, the chemical heat effect of reaction makes temperature rising in the stove, can pass through 1#, 2#, the variation of 3# thermometric galvanic couple 16 temperature displayed this moment, adjusts induced current power to guarantee the induction furnace temperature-stable through watch-keeping cubicle 10; In addition because industrial current/voltage daytime and night electric current fluctuation, also can cause fluctuation to furnace temperature, should regulate induced power in real time in the hope of temperature-stable in the stove.
At last, continue cool to room temperature through the charge graphite charging tray of blow tank under nitrogen protection, the sampling analysis composition goes out report according to one's analysis simultaneously, and product transports packing shop finishing packing to.