SU1634728A1 - Process for continuous electrolytic galvanizing of long articles - Google Patents

Abstract

The invention relates to electroplating, in particular, to methods of continuous electrolytic galvanizing of long products, and can be used in electrolytic deposition of protective zinc coating units on continuously moving products, for example, in galvanized strip and wire aggregates. The aim of the invention is to reduce the operating costs of the start and stop stages of the zinc process. The method of continuous electrolytic galvanizing of long products in an electrolytic electrolyte sulphate electrolyte using insoluble anodes includes the start-up stage, which is carried out by supplying electrolyte containing zinc sulfate 300-350 g / l and sulfuric acid 40-55 g / l a reactor in which zinc metal is dissolved, where the electrolyte is kept for a time sufficient to heat up to 50-55 ° C and to change the content of zinc sulphate to 350-400 g / l and sulfuric acid to 2-5 g / l, after which circus is performed the electrolyte passes through the electrolyzer, tank and tank until the P tank is set to 50–55 ° C, as well as the main step in maintaining the concentration of zinc ions at a predetermined level by circulating electrolyte between the tank and the collector and the reactor tank h a shutdown stage at which electrolyte circulation is disconnected between the collector tank and the reactor tank and galvanizing is carried out with electrolyte circulation through the collector tank and electrolyzer, the sulfuric acid content in the collector tank slots up to 40-55 g / l. Supply of electrolyte with high acidity at the stage of launching into the reactor tank for heating, and from it directly into the electrolyzer and shutting down the circulation of electrolyte between the collection tank and the tank reactor, with increasing acidity at the stop stage, reduce operating costs by saving heat carriers and refrigerants. 3 ill., 1 tab. Ј (I ZUY. OZ 4 v | Yu

Description

And the subject matter relates to electroplating, namely, to methods of continuous electrolytic galvanizing of long products, and can be used in units of electrolytic deposition of protective coatings on a continuously moving article, in particular, in units of galvanizing strip and wire.

The purpose of the invention is to reduce operating costs at the start and stop stages of the galvanizing process.

The method of continuous electrolytic galvanizing of long products in an electrolyte with an acid sulfate electrolyte when using a non-flowthrough polymer includes the start-up phase of i -lori, jj that psdach electrolyte containing n-rioxidine and nink 300- ZO g / l and sulfuric acid 40 -55 g / l, Sak-reactor, in which metallic zinc is dissolved, where it is kept under control for a period of time sufficient to heat up to 50-55 ° C and about 353-400 g / s l and sulfuric acid / g; l-5 g / l, ate what is done. (nsSulchpu, pass the electrolyte sequentially through the electrolyzer, the collection tank and the reactor tank until the temperature in the collection tank is 50–55 ° C, the main step in maintaining the concentration of zinc ions at a given vpoE7ip due to the circulation of electrolyte - i ADU by a collection tank tank and a shutdown stage at which the circulation of electrolyte between the collection tank and the reactor tank is turned off and the echek: rolite is poured down between the collection tank and the electrolyzer, in the collection tank e sulfuric acid to 40-55 g / l.

The essence of the inventor is as follows. First, the electrolyte composition x 7NlO 300-350 g / l with an excess acidity of 40-55 g / l is supplied from the blocker-collector to the reactor tank. In the tank reactor, the electrolyte is heated by the reaction of chemical ignition of metallic zinc, at i the concentration of ZnSO 7H2 was adjusted to 350-400 g / l, l acidity to H2S04 to 2-5 g / l. The electrolyte heated to 50-55 ° C is fed directly to the electrolyzer until the working temperature of the whole electrolyte mass is established,

located in all circuits.

When the zinc metal is dissolved in the tank reactor, the following reactions occur:

2Zn ° - 4e (anodna)

4НЦ

(cathode)

five

0

five

0

five

0

five

five

0

0

herewith due to the availability of free

at

SO ions in the electrolyte is formed by ZnS04 ' 7H20.

C In the proposed method, the galvanizing of articles is carried out with insoluble electrodes by dissolving zinc metal in a reactor tank.

Galvanization in a constant operating mode is carried out with continuous electrolyte circulation between the collecting tank and the electrolyzer and between the collecting tank and the reactor tank. This allows maintaining a constant concentration of the electrolyte in the collecting tank in the galvanizing operating mode, since it dissolves zinc retains its constancy in time until complete dissolution, i.e. By selecting a certain excess of zinc (its surface) in a bikO reactor, equality of reactions can be achieved: how much zinc is deposited on the product, how much will it dissolve in the tank reactor.

The selection of the amount of kick in the reactor tank is carried out according to the capacity of the line for applying a zinc coating to the product,

The exact speed of electrolyte circulation is determined during commissioning, during the start of the galvanizing line of products. It depends on the size of the pieces of dissolved zinc (pigs, anodes, clean, plates, etc.).

This method of galvanizing involves the use of a high current density (up to 240 A / dm), which is a tendency of modern continuous aggregates. In connection with this, for the zinc plastering the use of the powder-concentrated electrolytes, which are used without additives at the time of INTRNISIVE mixing.

Turning off the electrolyte recirculation between the collector tank and the reactor tank before the end of the process allows the accumulator to accumulate,}. in the electrolyte and produce electrolyte that is in the collection tank to the lower limit of the working concentration of 350 g / l ZnS04 7H20, which reduces the krnstzliliatsiya elehgropch i with if L / l - decin

Such a technical IMC chooses, in subsequent years, to control the power of the controllers directly and the operating system with the operating temperature and operating costs, for the cancer of the electrolyte before the operating time. those cher chd

According to the well-known / method, the heat consumption + Q in the period of the electrolyte rtzp pr i i is limited to the first-order OAVS. At point C ikn iaxn, an emitting heat exchanger (for removing heat left) and production is Qr — Q (direct CDN. C m UY- liquefying leaks, galvanized em is transferred to the prior mode, while DK, as indicated, heat exchanger heat exchanger. When you stop the cycle process, the cooling heat exchanger is switched on - right LK. The uDKL rectangle shows the amount of heat ia (.p.joule heat + charge from pirrpope- nor metal in the IK-Rector), the removal of what is happening in r ochei me process, tsichyuvanit ..

According to the proposed method v (. 1) in the initial period of time, t. Because of the heating of the electrolyte, not p C v v, but the eceptrolite is heated, it is direct i C I metal zinc g sulfur ion acid in the tank reactor — direct CR. This period lasts. rot, Chatham electrolyte from the reactor tank to the electrolyzer, where the inkyi LCI galvanized (at point R). In DS-SNRM M (right TR), the whole (HI - from the e-collector is allowed to flow 0 0 mtr and upon reaching the working pressure pir; electrolyte in 5ake-ss, np o, cooling - chi bmsl ni (ip i-ma RE).

When operating, the chillers remove heat by 2 1 and 2 hours 2 hours before the end of the cycle, turn off the reactor tank, and lower / r the amount of cooled water, the heat exchanger (MN).

Subsequently, TQTIIO is diverted to the left heat generated in the jj ectrotor (direct MP), and during the zinc-coating process, the cooling heat exchanger is turned off (direct PT),

From the sequence diagram it can be seen that, according to the proposed method, the heat is not used for preheating the electric motor.

/ n

 till, I

I I I I I I I HI I 1

Ig L -1 (.

T (I OS I h Оi) x 1 П Ч L i (I п Ч - i

, I 1 shM).

i1 i t i i. I i to a -I 14 i icxci i, i rin

JGT r Ic PC And III

w ii. i t pi

It i IIHI T1 c- t t I C41 J1 1 t

i i and i; ir tr, 5 - L t i

i 1 T K II 14 1 I iM l

 i OTOi I U L i II

r C lo JiJM P) f × (l (,, „,

-lOr f PT 1 T POM I 1 and L 11 I 1

I 1 1 T TO G1 T I.

J I f J (. DJ K P

 ; one . G 1f Hi.1Ht T Tl L And 1

u 1r with jti. -n H1 Ft L

zs p j. with i i and ITO i ° ii m it i p T i pin (op 4, ti with

I I 5, b Tl i, L, i iMIJIOC Hi / I

 CTL 8, l and 10. Дт ъ с - 25 | гс and i г е i «j cni-INIJ, t r n

i pi i o l and f - v- L t T and /. PG L. I CMtJptH iivrToi I g and.

1 P I g / | 11 rpt, 1,;

r l (I i) (G AD G, P PO HU- j I 1 1 I f 1v hHI KOM PGG gb - PC І II ilOii) fi OilТ 1

U 60 tj P 1. T i i, M 1 1r, 11 .1

t i - h v D - t hch.t mej 1 e lOjpc dot r uiTPj i h i o i, r tip 1, D) pi 4 t M Hi cl G i TTI j

JjKIf11f 1C O 4t i 1) P

r irm n) i what ci T r. 1GG II 1JI1 li

i 2. i p r f p p p from the PCSD to HI-i rm

DG) I IT i, (, ijc I С TK C T

TOp t I J -i OOll, (Vr-cUIQlH pi

r u i iK j i L 3.

 rip g p i f, TI / (7

l ij of - p-c45 t igp 1 i with ri f -i -vtii h i ei Tpori liG 1 O) P (. P I i O G T g-, I 6 Jt - if ci4TOl u it i 1 5 ce ; iu i i-ncficii

h n KL.-cbopi-x b - 16 for supply - auxiliary valves nt 5C i i not ioi pz u t).

1 s 10 t j t i stumps o1 n v p gg for th j j t ii i5 u i tt m i.

(h about R b IK-re h hc m i i jiPierK, i n with r i s i i t i,} cpiv "41 p i. HHMGH (H1 lCHiI-Pb 1,. HF i u Oi o

ur pp n ssg 1gkcho p hchtam t walkable to it-fTBO ti rn-i-yuy pore i i, t i t (rF i i -in tps-sh and

350 g / l of ZnS04 and excess 50 g / l of the finished electrolyte is pumped through an additional pipeline into the electrolyzer 1, and from there by gravity through the drain pipe (with the open control valve 14) the collection tank 5 is stuck together. After transferring the electrolyte from the reactor tank 4 in the tank-collector 5 overlap the drain pipe control valve 14.

The galvanizing electrolyte from the collection tank 5 by pump 9 is pumped through the pipeline through the filter b and fed into the reactor tank 4, and the excess electrolyte through the pipeline into the collection tank 5. Due to the free sulfuric acid in the electrolyte, the zinc plating occurs j. tvKHi) sulfur cyglobulla 1 ti with MRI ingots, altogether about tsyyg, n due to nagosom 8 through an additional pipeline, podiyu1 p R.ROCHII gap 3 between electrode 2 and strip in the electrolyzer 1 and c .: ich yug process caused zinc spoil the strip. The number of iBc-emogs electrolyte is determined; control valve 2. From the electrolyzer 1, the electrolyte through the overflow pipe is drained into the collection tank. When the electrolyte reaches its working temperature, the pump 8 is turned off and the control valve 12 is shut off, and the control valve 13 reduces the amount of electrolyte supplied to the reactor tank 4. At the same time, the pump 10 is turned on and the electrolyte from the collecting tank 5 through the heat exchanger 7 is connected through the pipeline I electrolyzer 1, adjusting the amount of electrolyte supplied by the regulating valve 11, thereby constantly the first working oe- they electrolytic galvanizing Poos. During operation, the zinc echegrolite is carried away from the cell 1 by a strip, which means that its level in the collection tank 5 is reduced. The control valve 16 is interlocked with the level gauge H of the collection tank 5 and when the electrolyte level reaches the bottom, water passes through the control valve 11 and does not automatically enter the tank 5. Supply of sulfuric acid to f reactor 4 is performed through control foam during operation. - til 15, which is interlocked with the concentrator C installed in the tank collector 5.

0

five

0

five

0

five

0

five

0

five

The estimated time of the pump is turned off and the control valve 13 is shut off, and the electrolyte is supplied to the electrolyzer 1 from the collection tank 5 with the tank-reactor 4 turned off.

When several units A, A, A are operated (Fig. 3), the first zinc electrolyte is fed to the electrolytic cell of unit A from the tank reactor 4 by pump 8 with electrolyte discharge into the tank 5. In view of the fact that during the deposition of zinc Joule is released the heat, the electrolyte enters the collection tank 5 with a temperature of 70-80 ° C, and the process of heating the electrolyte in the collection tank is accelerated. When the working temperature reaches 50 ° C in the collection tank, turn on the electrolyte supply to the Aj and AZ units and carry out the process of applying the coating by pumping electrolyte from the collection tank 5 to the electrolyzers of the A, A, A, A cells with simultaneous circulation of electrolyte between the tank -reactor 4 and collection tank 5.

The operation of three units on the electrolyte of the same composition creates conditions for a stable and uniform deposition of zinc coating, especially on the wire, since the wire has a surface several orders of magnitude below the surface of the strips and requires a volume of electrolyte galvanizing within 1-3.

An example. The proposed method was tested on a galvanic zinc-plated armored cable strap.

Zinc tape was carried out in two stages of adium.

At the first stage, the tape was galvanized by a known pro-1 method to totip, i.e. with the preparation of galvanizing electrolyte in a stand-alone tank reactor, when the electrolyte is heated by a heat exchanger up to 50 ° С, and the electrolyte is adjusted in the tank reactor during operation.

In the second stage, the tape was subjected to galvanization by the proposed method.

In a 6.5 m tank-reactor, 4 tons of zinc metal in ingots were loaded, 4 m of water was poured in, and sulfuric acid was added in batches, the weight of 1.84. Then the electrolyte was pumped to the collection tank. 16 m galvanizing electrolyte with a concentration of ZnS04.7H20 350 g / l, HZS04 55 g / l was prepared.

Galvanized gg tape with a tape width of 220 mM „1.0 mm thick from.St.Z, dpigavuiuym TM unit with a speed of 30 m / min. Zinc was deposited on a 3 micron thick tape on each side with a straightener of 1–16 kL.

The electrolyte from a 16 m collection tank is pumped into a tank reactor. 10 minutes after filling the reactor tank, the electrolyte temperature rose from 20 to 50 ° C and the electrolyte with this temperature was fed to the electrolyzer. The electrolyzer consists of 14 cells with insoluble electrodes suspended from lead. From the electrolyzer, the electrolyte was poured into the tank: born. The temperature of the electrolyte in the tank collector reached 50 ° C through AO. reduced dz 5 m / h. After 4 h of operation, the supply of electrolyte to the reactor tank was stopped and the electrolyte was circulated only between the collector cell and the sump pump for 2.5 h, the unit was stopped.

The composition of Elektrolit Ninkgva.pn after stopping the unit: 355 g / l, F2SO 51.5 g / .h,

Exceeding the concentration of ZnSO.x x above 400 g / l leads to enhanced crystallization of the electrolyte, when cooled to 20 ° C (shut-off valves clog, and a decrease in the concentration of electrolyte 1 ZnSO,}

below 300 g / l dramatically reduces the performance of the zinc process.

An excess of the excess acidity of B1 over 55 g / l in the electrolyte leads to a sharp increase in zinc crystals during deposition and reduces the quality of the coating due to an increase in its hardness. Reducing the excess acidity below 40 g / l in the electrolyte increases the time the electrolyte is heated in the reactor tank, which removes the performance of the galvanizing unit for long items.

A decrease in the concentration of free H.SOjj below 2 g / l increases the crystallization of the galvanizing electrolyte when cooled to 20 ° C, and the excess concentration of free in electrolytes

ten

in 1dure of electrolyte temperature

Q

55 C leads to increased corrosion

15

3472310

Those VN1LS1 5 g / n leads to that a significant amount of hydrogen is supplied by an electrolitzer together with electrolyte, which leads to an uneven - iiL crji burn (formation of hydrogen - Hbix MScH in the interelectrode space of the Element; trolizer).

Prép

equipment and an increase in the size of zinc crystals during coating, and a decrease in the temperature of the electrical supply below 50 ° C leads to a decrease in the current efficiency during electrolytic application of the gink coating on long products.

The properties of the zinc coating obtained from the electrolyte of the proposed composition are practically not different from the properties of the zinc coating, derived from the known acidic iktropites of zinc coating (see the table).

A zinc coating was determined by a known method.

The porosity of the coating was determined by dosing 1 sample for 60 seconds in an electric detergent of the composition: CfG (SC) 40 g / n, 2 g / l at room temperature cm-cm. As the anode, lead is used. The number of pores was calculated by the number of blue points of the turiOulevoy syn. The strength of adhesion to the substrate was determined by the method of applying a grid of scratches with sides of a square 2 mm. The depth of the spherical hole is determined; by a known method. 11, t roho atost was determined using a Kachibr-type profilograph. Corrosion tests were carried out in a salt fog chamber, in a solution of 5% Nad at t 60 ° C.

20

25

thirty

35

40

45

50

55

It follows from the table that the properties of the zinc coating obtained from the electrolyte of composition (II-V) are practically the same as those of the zinc coatings obtained from the known (1, VI) acid electrolytes of zinc coating.

The method allows to reduce the operating costs at the start-up stage, since it does not require the costs of the heat carrier for heating the electrolyte, and at the base stage, where the flow of cooled water is reduced due to the absence of the need to remove the heat generated in the baht-reactor.

eleven

Claims (1)

Invention Formula A method of continuous electrolytic galvanizing of long products in an electrolytic cell with electrolyte sulphate using insoluble anodes and maintaining the concentration of zinc ions at a predetermined level due to electrolyte circulation between the collection tank and the reactor tank, in which zinc metal is dissolved, characterized in that , in order to reduce operating costs during the start-up and shutdown stages of the zinc process due to the use of .- heat utilization of the chemical dissolution of zinc, the start-up step is carried out the supply of electrolyte containing zinc sulfate 300-350 g / l 163472812 and sulfuric acid, 40-55 g / l, in a tank reactor, in which it is kept for a time sufficient to heat up to 50-55 ° C and change the content of zinc sulphate to 350-400 g / l and sulfuric acid to 2-5 g / l, after which it is circulated, passing the electrolyte sequentially through the electrolyzer, the collection tank and the reactor tank until the tank 5 is installed ten the temperature collector, and at the stage of shutdown, the electrolyte circulation between the collection tank and the reactor tank is turned off and when galvanized with electrolyte circulation between the collection tank and electrolyzer, the content of sulfuric acid in the collection tank is adjusted to 40-55 g / l. .- r-5 the temperature collector, and at the shutdown stage, the electrolyte circulation between the collection tank and the reactor tank is turned off and the galvanizing content of the electrolyte between the collection tank and the electrolyzer is adjusted to 40-55 g / l in the collection tank. P "composition electrolyte, g / l I ZnSOj-7NeO-300 Ng50 "(s) -1.0 U ZoSO, c7HeO -350 ft, SO, (s) -2.0 HI ZnS04-7H40 -400 H4S04 (s) -5 IVZnS04-7H 0 -300 UtS04 (s) -40 VZnS04 7HtO -350 N, 50 | (s) -55 VIZnS04-7HtO -350 NK4) "r4-30 pH - 4 Zinc coating properties I time FIG. one Editor M.Nedoluzhenko Figz Compiled by V. Medvedev Tehred M. Dndyk Order 734 Tyra 401 The VNIIPI State has many committees for inventions and discoveries under the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, Raushsk iu6., D, 4/5 Corrector K.Fapoiin Subscription