DE1929549A1 - Method for operating a zinc-lead shaft furnace - Google Patents

Description

"wt-Λπνν DInI.» ro guy · A

Wi /

Munich-PullachjH. June

BREVETS METALLURGIQUES, S.A.,

Boulevard des Perolles 4-, Friborg, Switzerland

Procedure for operating a zinc / lead shaft furnace

The invention relates to a method for improving the Wi efficiency of a zinc / lead Schaohtofens, which with kohlenhalti-jgem Fuel and a zinc oxide and Blexoxyd containing sinter is charged, and in which a preheated oxygen ■ Containing gas is blown in by tuyeres near the furnace base becomes fluid while below the wind forms. BIe :. and slag usually periodically, but also occasionally continuously withdrawn. The zinc oxide of the batch is mainly reduced to zinc vapor, which together with the mostly consisting of carbon monoxide, carbon dioxide and nitrogen Exhaust gases are drawn off through an exhaust opening or several such openings above the charge surface and one or more. Condensers is fed to here by spraying to be condensed with molten lead.

The inventive method for improving the efficiency provides for a control of the relative quantities and temperatures of the furnace throughput and the introduced combustion air as well as an evaluation of the control measurements and the respective furnace outputs based on one for the important physical and chemical basic factors Norm «, albeit the full coverage and explanation of all The chemical reactions taking place in the furnace are extremely difficult, but those on which the invention is based has emerged Investigations show which of these reactions are to be regarded as important and what their special features are. A Korm has been developed on the basis of this knowledge which is decisive for the furnace performance and into a

009817/1250

for the operation of a program-controlled computer (Computer) suitable mathematical form can be brought.

The following important reactions take place inside the furnace:

First of all, it arises from the burning of the coke on the. Wind forms mainly carbon monoxide and some carbon dioxide, due to the following exothermic reactions:

G + 1/2 O ₂ - GO (A)

CO + 1/2 O ₂ = CO ₂ (3)

Part of the carbon monoxide formed reduces the zinc oxide to zinc vapor according to the endothermic reaction: ZnO + CO = Zn + CO ₂ (C)

In a slightly higher furnace level, the carbon dioxide from reactions (E) and (C) reacts with the carbon of the coke with the formation of carbon monoxide, according to the endothermic reaction:

C + CO ₂ - 2 CO (D)

Partly in the zone in which reaction (D) takes place, but mainly in the upper furnace zone, in which the sinter - normally it is cold if it comes from a storage point, but occasionally at a higher temperature, to whom it is supplied directly from the sintering plant - and - usually occurring with a temperature of about 800 ⁰ C in the oven - coke by the rising gases heated advertising, the, reflected on the surface of the downwardly bewegenjden batch little zinc oxide from the exothermic reverse reaction (D) down:

Zn + GO ₂ - ZnO + CO (E)

In the upper furnace zone, too, the hydrogen oxide is converted into carbon monoxide reduced:

PbO + CO «Pb + GO ₂

009817 / 12S0

BATHROOM 0RK3INAL

The physico-chemical basic standard assumes that dei furnace operation is primarily dependent · The other reactions β from the heat and Hass potential and the speed with which the Reaktior D expires, E and F as rapid _t to be substantially can be judged according to the mass throughput · This results in an equilibrium zone in the furnace in which the gas and the solids have the same temperature, so that there is a chemical equilibrium between the gas and the solids with regard to the reactions 0 and E.

The inventive method for operating a zinc / lead shaft furnace consists in the continuous monitoring of the values for

a) the zinc / carbon ens to ff «ratio in the batch,

b) the preheating temperature of the combustion air,

o) the ratio of slag formers to carbon in the batch,

the

d) the composition / gases emerging from the furnace,

e) the zinc content of the slag and

f) the temperature of the liquid exiting the furnace slag

and in the setting of the zinc / carbon material ratio in the charge and the preheating temperature of the combustion air; to a maximum zinc excretion due to the relationship:

υ ^

Κ «(a _o

D)

where R _z - zinc precipitation,

V - a constant,

S ₂ »Weight ratio of the slag formers to the sink

in the batch.
τ, 1 1
* "TT *" zinc / carbon ratio in the batch,

009817/1250

BATH ORIGINAL.

E ¹

ρ +

«A constant,
Λ a the number of moles of carbon burned each

Oxygen atom of the combustion air,
t the preheating temperature of the combustion air,
• bj- and ap. - a _r ■ multiples are ·

Further details of the invention emerge from the following Description based on the drawing. In this show:

Pig «1 shows a schematic longitudinal section through one of the invention underlying shaft furnace;

Pig, 2 a Compute r-Abl aufpl on and

Pig · 3 a calculation program for the computer.

With the help of the mathematical equations to be established
a starting point for the predetermination of the effect on zinc separation resulting from changes in the operating conditions, the initially static
The starting point is then adapted to the dynamic behavior of the system.

The furnace performance is determined from two of the following Factors:

a) the amount of zinc fed into the furnace,

b) the amount of zinc fumes released from the furnace and

c) the amount of zinc escaping with the slag »

These factors are calculated as molten zinc «The
The amount of lead going through the furnace at the same time has little effect on the way the furnace works
Zinc smelter. ITUsually it is between. 1/3 and 1/2 of the weight of zinc entering the furnace

OO 9 817/1250

BATH

Of the three aforementioned factors, the amount of zinc vapors escaping is within a short range. extremely difficult to determine, for this reason the zinc- yield calculated from the zinc input and the zinc loss »

Calculation of the static starting point

The functioning of the zinc shaft furnace is fundamentally dependent on the thermodynamic requirements due to the heat flow and mass throughput as well as the reaction speed for the reaction 0 + GO2 ^a 2 GO given at the beginning under D. The other reactions are lightning fast. It has already been pointed out that over a considerable furnace area, namely in Zone II of It'lg.1, gases and pesticides are in thermal and chemical equilibrium «

The chemical equilibrium for the pin reduction is expressed by [P ₄ GO ₂ J [P. ZnJ

[P.GO] aZnO _c

where P refers to the relevant partial pressures and There is no function of the temperature

The I'akbor of the solid zinc oyster (aZnO) is set as a bin

In the same) zone II the endothermic reaction between the carbon and carbon dioxide takes place (reaction D), and the G light weight is obtained by the rapid oxidation, of the zinc ** by carbon dioxide, which is an exothermic reaction trades _β Above the compensation zone, there is a hurry on the floodplain. j preheated equal temper atui *, and. swar by the icoiübiniorhu G qs cooling and zinc return xyrlation ,. .wherein -.las an «toilliya ratio of the two processes of the relative advertisements for d'3u. Heat and material exchange dependent on iab, this preheating

009817/12 SO

BATH ORIGINAL

zone is illustrated in Ilg »1 as Zone I, Bs becomes of it it was assumed that the Ghiltoii-CQlburn analog technique is decisive for the relationship between the exchange of heat and hydrogen is, and that the radiant variae are not taken into account can »Since the batch prewarwäraiung z» T, mi. t a gas cooling is connected, the gas leaves the batch in a non-uniform manner. moderate condition, and it is therefore in order to prevent a greater deposition of zinc oxide in the gas vents The addition of air above the batch results in this in front of you exothermic reaction of atmospheric oxygen with carbon monoxide heated up,

It seems appropriate to equilibrate zone II and the one above it lying preheating zone I to be brought separately,

a) The equalization and melting zone
"C ^ II and III according to EIg.'T)

The input variables of this zone are ■ ~ -: ■■; ■ -

1 »the air preheating temperature T and ■

Ir

2 «the batch temperature T, while

the output variables ■ - ■: ■■■ .-- ■

1 »the gas equilibrium temperature T and 2 »the slag tempera door T, are»

If the zone is always referred to as "Liinkelsbrahlk", the overall reaction in the zone can be expressed by; Mi ₂ + (1 + P) C + 1/2 Op + zZ-iiO - zZn. * - (ap) GQ _? + (1 + 2p-z) CJ0 + E Hiurln i.-jt ζ the Ivfolzahi gea-.hmoIkonen zinc per oxygen atom of the combustion air j (ρ ι- 1) the number of burned carbon, per oxygen atom of the combustion air and R the ilevt djr inert Components are above the oxygen in the combustion air, that is, the air value, dex * in the following calculations with 1.38 * 1 an ^ acetate becomes »In a killfalctor

009817 / 12S0

BATH ORIGINAL

the equilibrium state is determined by one for the zinc oxide by:

K- [z (z-p)] / [(1 + 2p-z) (2,881 + p + z)], (1)

where K is the equilibrium constants, "based on the Equilibrium temperature T according to the equation:

HT _k 1nK - -47.34-5 + \ (£ 1.23 - 2 «92 1nO? _K ) (2)

with T, «T + 273.3.
is. β

Equation 2 contains the value of the free energy at the .Temperature T ^. for the reaction ZnO + GO - + ■ Zn + CO ₂ .

A further Equation can be formed «Add the heats of reaction the temperature T «± ä, furthermore the intrinsic warmth for heating the combustion air from temperature T to T and the solid slag from the temperature T "to T- as well as the latent heat for melting the slag, it results following equation!

z (4-2.110 + 10.17Te-i3.02T _Bl ) - 21. 750 + 1. 37T _e -p (42,370-2

2607T _e +126.4) -

_{sle fl e}

- (T _e -T _p ) (16.75 + O »OO121) (T ₆ + T _p )), (3)

where Z is the number of zinc oxide molecules per oxygen atom of the combustion air enter the equalization zone, and S the weight 'of the waste products (in kg), which per kg atomic Oxygen of the combustion air enter the equalization zone, mean.

In this equation there is a heat loss of 4 kcal per 0.454 kg of oxygen has been added to the combustion air.

The equations 1 »2 and 3 can be used to calculate ζ and T are used if the values of Z, S. p, T and T. are known are. This calculation was carried out using an Elliot-503-0ompu-

■ te rs

009817/1250

BATH ORIGINAL

ters, the program of which is shown in FIG. 2 is.

To calculate the new value for T _Q , equation 2
converted into:

T _e (New) - 47.345 / [51.23-Elnk - 2.92 ln (T _e (old) +273.3)] (4) Is is a fast converging calculation, for which a fourfold repetition is sufficient in any case · Will that Procedure reversed, ie if equation 3 is used to calculate T ₀ and equations 1 and 2 are used to calculate % , the result is a diverging one
Calculation »The value for T lies between 950 and 1150 ⁰ C um mainly depends on the T and p values.

b) The Ohargen preheating zone

The following equations apply to this zone!

dl / dx - -h (T -T) (5)

dp ₁ / dx - -hDi In [(1-P ₁ ) / (1-P ₁ )] (6)

He (dT _s / dx) - Hg (dT _g / dx) + H _t dy / dx (7)

P ₁ . (».Y) / (2,881 + ρ + ζ - y). (8th)

P ₂ - (1 + 2p-z + y) / (2,881 + ρ + a - ψ ) (9)

P ₃ «(β-py) / (2.881 * ρ + ζ - y) (10)

K - P ₁ P ₃ / P ₂ t (12)

where P ₁ , ρ «and ρ, the partial pressures of the zinc, carbon monoxide
or carbon dioxide in the gas phase, P ₁ , P ₂ and P, the same part presses on the solids pool, T the gas temperature, T di <solids temperature, χ the zone height inside the furnace above the upper limit of the equalization zone, ψ the weight $ in kg) des

009817/1250

oxidized zinc per kg of atomic oxygen in the combustion air between χ * 0 and χ «χ and D. denotes the relative diffusivity of the zinc", where JL is obtained by

D ₁ »0.81 / [o.81 (P ₁ + P ₃ ) + 1.0 (p ₂ + P _n -)] '(13)

Equations 5 and 6 give the values for the heat and mass flow rate through zone _t , the constant h contained therein referring to the Ghilton-Colburn analog computer and it is assumed that the Lewis number is one and the partial pressure of the inert gas remains essentially constant. Equation 7 represents a heat balance over the partial height dx, where H and H are the heat value of the batch or »

s g

of the gas are and H ₊ . the heat of reaction of the reaction

Zn + 0O ₀ 2- ZoO +00 at temperature T is · The equation & s

11 is an overall calculation of the gases and vapors on the surface of the batch and, like equation 13 », assumes that that the diffusivity of zinc vapor and carbon dioxide is about 0.81 of the diffusivity of carbon monoxide and has nitrogen. Because of the fast running There is a reaction between zinc and carbon dioxide on the solid surface for the gas a state of equilibrium, this results from equation 12, according to which:

E (! D _a +273.3) lnK - -46.345fr (0! _A +173.3X51.23-2. 92 In (T ₈₊ 273.3)).

This suggests that the oxidation is exclusive at the I solids surface is going on, which is a heteropolar reaction is involved

From the differentiation of equation 8 and the conversion the equations 5 »6 and 7 result in:

dy / dT _s «[H ₃ -Hg (dT _g / dT _s )] / H _t (14)

dy / dl _s - H ₃ / [ü _{! E} - (H _g (2,881 + p) (T _g -T ₃ ) / (D _i ir (2,881 + p + zy) ² ))] (15 where U «1n C (IP ₁ ) AI-P ₁ ) J results from the equation

009817 / 12S0

[(2.88i + p + zy) -e ^u (2.881 + p)] [(2.881 + p + *. Y) -e ^u (2 «881 + 2p)] ·
- K [(3.881 + 3p) e ^{o # 81u} - (2.881 + p + ay)] (2.881 + p + a * y) (16)

These differential equations have the following boundary conditions T_ - T_ - T , y 0 (initial value j anf)

5 B β

2 - T- (Bndwert \ end *)

where T ^ is the solids temperature at the charge surface. The total amount of reoxidized zinc within the entire zone (s) is given by

(dy / dT _e ) dl mol per oxygen atom in air.

For the computer solutions to the equations it has been found to be
Proven to be appropriate to equation 16 in the following Ibrm
convict j

U * 1n 02
_# ^# «DU / d 02 - [1 / O2J (17)

dO2 / d K - - [(3.881 + 3p) 02 ⁰ · ⁸¹ - 01J / [oil (5.762 + 3p) -

- 02 (5.762 + 4p) (2.881 + p) + 0.81K0102 "^ * ¹⁹ (3.881 + 3p)], (18) where 01 - 2.881 + ρ + ζ - · y *

dK / dT _s - K ((23851.V (T ₈ + 273) ² + 1.471 / (T ₈ + 273.3)) (19)

Since the initial value door T_ - 2 _a · corresponds to the initial ^
value for K to the one who calculates for the compensation zone
becomes (s «Equation 1)«

02 (begin) · 1 and U (begin ·) «0.

The solids end temperature is the mean value from the sintering temperature of 15 ⁰ O and the KJok temperature of 800 ⁰ O
The associated "thermal radiation" changes, however, the value
for Τψ9 This was not ■ taken into account in the above calculation »This does not change the form of the

009317/1250

Polynomials (»one-unit quantities) influences» although si oh. Ua- * correctness of the theoretically calculated coefficient can result, because the Auagangsbasis or «the model for the control of the furnace cycle only needs the sun of the polynomials * w- rend the coefficients result from the measured individual values of the system «

The equations 14, 15t ^ f »^ ⁸ and so on. 19 are solved by a simple repetition process. Here, the solid "temperature range (T _# - ^> T _f ) is divided into several" sub-ranges 4- ^ a ^ierw and based on T ₀ * T * e as well as on the basis of the values for p , ζ and K _{Mf #} the values $., ^ G2, / U,

A j is calculated and from this new values for T ₉ T ₈ , y _f K, U and 02 are obtained «This is repeated until T ₈ -» _{f is} at f * η · Then the value for ^ T _{8 is} halved and a second Repetition carried out to determine a new value for η " Further repetitions are carried out by halving the values β J [ T until η remains constant within +1, Ox 10" * "This calculation method converges very quickly and the number of repetitions fluctuates according to the Aafan values for % and ρ «between 2 and 5 · The initial phases ·»

number was 16 in each case, i.e. repetition

- Tp) / 16 for the first

o) Pair model of the whole shaft furnace

The two groups of the model can now be combined to form an overall picture of the shaft furnace. The input variables of the model are B, Sr, T, ρ and T _fl ^ · Here D is the weight ratio of the zinc to the carbon in the batch and Sr is the weight ratio of the slag formers on the coal ens to f in the batch · The output variable to be determined is the zinc loss in the slag «From D and Sr, the values for Z

00S817 / 1250

and S ₉ , which are input variables for the equalization and melting zone of the läbdelles, are calculated from equations j

Z - 12.01 D (p + 1) / 65.38 + η (20)

S «12.01 Sp (ρ + D (21)

Because of the dependence of the value Z on η, a further repetition process must be carried out for the overall model. The relevant computer program is illustrated in Mg. 3.

This calculation also comes together quickly, with only three or four repetitions are necessary to get the required degree of accuracy for ζ and η. From ζ and η can the value Ir can be the weight of zinc losses in the slag per unit weight of added carbon according to the following Equation to be calculated:

L-D- 5.444 (z - n) / (p + 1). (22)

With values for ζ and η an accuracy of 2.0 x 10 becomes for Ii a value with an accuracy of + 0.001 is obtained. With on an Elliot 503 computer programmed in Algol, each determination of L took about 5 seconds.

Since the model equivalents are too complicated ^ to be able to be brought into a multi-part jbrm in an analytical way, the corresponding values for L were calculated _{as a calculation basis for p, T and D from three calibration values for Sr and two guide values for T sl} Formation analysis the Eorm of the polynomials determines which result (s) is suitable «

The best polynomial form has proven to be L - B ₀ + Si ₁ P + a ₂ T _p + a ₃ D + a ₄ ρ T _p + a ^ p ²

ZW is the loss of zinc in the slag per percent by weight of the

009817/1250

Zinc introduced into the furnace, the result for ZW is the

Equation:

ZW - S ₀ + i ¹ Ca ₁ P + a ₂ T _p + a ^ + a ^ pT _p + a ^ ² ), (24)

in which Ϊ ¹ - 1 / D is «

Typical values for the constants, namely at Sr - 0.80 and ID - - 1300 ⁰ O, are given by the following equation:

ZW - 125.5 + Έ (263 8ρ - 1.721 x iO ** ¹ a} _p + 2.37Ox 1O ^-1 TpP - 908.3 ρ ² - 54 * 32) (25)

The accuracy of L is here + O.OOl and that of
ZW 0.1 #abs.

D) The degree of carbon burn

The variable ρ in the above equation for ZW is
not an independent quantity, but an expression for the amount of carbon burn per unit of air. This depends on the following factors:

1. of the ratio of the 00 and GO ₂ produced in the incineration and Sohmeltzone III as well as

2. the degree of carbon gasification in the balance zone II.

The first of these two factors cannot be determined mathematically exactly, but formulas for the degree of carbon dioxide gasification are known and values are available for the kinetic constants. When using coke as fuel, the general equation applies to the reaction 0 + CO ₂ - *> 2 00

E - K ₁ P GO ₂ / (1 + K ₂ P 00 + K _$ P OOgl, (26)

in which the Eeaktionsergebnia iet, expressed in kg per minute, at and per Sg carbon. As is well known, the implementation regardless of the gas velocity · With a slight reduction in accuracy the previous equation can be simplified

009817/1250

H - K ₁ P (3O ₂ / (1 + K ₂ P 00), (27)

whose values K ₁ and K ₂ sie, result from;

K ₁ - 3.56 χ 10 ^ (-4.24 x 10 ⁴ / BT ^) (2B)

K ₂ - 3.35 x 10 "| (4.68 χ 10 ⁴ / RO ^), (29)

where T ₁₅ . the absolute temperature is These values apply to coke dust, but the value K ₁ for lump coke is about half as large, ie

log K ₁ - 3.250 - 0.921 x 10 ⁴ (1/03 ^) (30)

log K ₂ - 7.475 + 1.036 χ 10 * (1 / T ^) (31)

Me values K ₁ and K ₂ were determined by experiments.

In a rail of the derailment zone, a bead of dx IuB (O _f 305 m) and a height of A square (0.091 m), the weight of the carbon is »100 A dx / (2 · 222 B + + 3.444) lbs (kg 0,4-54-) so that when the wind amount of clay-V Kubito IUSS / min (0.028 Jt / mln?) Mfferenti the equation al for ρ is:

dp / dx m - (2.48 χ 10 ⁴ BA) / Y (1 + 0 * 64-5 »), (32)

where B results from equation 26 and χ in downward « direction of the furnace is measured.

If ρ decreases downwards in the furnace, then you must see them too Change values * and T so that a chemical and thermal equilibrium is maintained. SUr maintaining the thermal equilibrium, the following equation applies:

(dp / dx) ^ + (da / dx) H ₂ + (d! D _e / dx) (H _g + H _fl ) - O ₅ (33) where H _{1 is} the heat of reaction for the reaction 0 + CO ₂ -> 2 00 - +42.367 - 2.09 T _e and

the warmth of the reaction

ZnO + CO - *> Zn + CO ₂ - +46,542 -. 2.96 T ₀ and

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H and H the heat content of the gas and the solids (each g s

Oxygen atom of the combustion air) mean «

Me maintaining chemical equilibrium will duroh the equations 1 and 2 determined «By differentiation and substitution results

+ 273 «3) ² - 1

- dp / dx (V (z-p) + VC2.881 + P + Z) + 2 / (1 + 2ρ * -ζ)) (34)

To obtain a GeauutMlanz for the zinc from the countercurrent flow obtained, the relation dz / dx ■ dZ / dx is to be assumed, (55) The values dz / dx, d! D / dx and dZ / dx are derived from dp / dx »

The initial conditions for these differential equations are the values T , p, z, Z and S at the head of the compensation zone _f as they were calculated when determining sw «The final state 1st χ * L_ ₉ where L. is the height of the compensation zone · For positive values of ρ can solve these differential equations "be made to the method used for preheating the other hand is similar for negative values for ρ the bill convergence very low · for this reason, the equations were calculated for each part value x (delta χ) using the Gills ·· Adaptation of the Runge-Kutta equations solved, and this method was used consistently in all IFallea.

Since the value for ρ at the head of the equalization zone (pT) is the variable to be determined, ρΦ values were initially applied in order to obtain a target value for ρ at the bottom of the equalization zone. For each of these values pB, corresponding coefficients for T and D received «This naturally required a series of attempts with sources of error, especially« although

the starting condition for the solution was, pB the variable that had to be set to a target value «

009817/1250

This was "especially difficult with negative pT values, though small pT deviations resulted in large pB country ranges. That The relationship between pi and D was similar to that between pi & en ρI and T, with the exception of the fact that one with D the accompanying change in pT was too small to be shown graphically,

Between. There is therefore an asymptotic relationship between pT and pB

+ division, ie that pT, since pB -> Ί§Τ -> pB and pB - * - -0.5, assumes a constant value dependent on T and D, where -0.5

P.
The smallest possible value for pB is and corresponds to a combustion to pure COp · D. The curves are best formed by polynomials with the sizes T, D, pB and 1 / (pB + 0.5) ι and a recalculation resulted in a good one Result with the equation:

pT - Si ₀ + eujpB + a ₂ / (pÄB + 0.5) + a ₅ T _p + a ^ pB ² + + a ₅ / (pB + o.5) ² + H ₆ T ₅ PB + a ₇ a? _p / (pB + 0.5) + agD (36)

Typical values for these constants are given by the equation:

pT »0.248 + £ | 6ä £ -pB - O.i56 / (pB + 0.5) + 2.21 χ 1 (T * T +

+ 2.78 pB ² + 1.31 x iO ^"2 / (pB + 0.5) ² - ρ · _Ν 32 x 1O * ⁴ T pB - 5 * 9 * x 1O ** ⁵ / (pB + 0.5) - 2:03 x 10- ² D (37)

These constants apply to L ₆ - 14 luß, A / V »0.0165 min.ft, Sr * 1.00 and T _fll - 1100 ⁰ O * The relationships between pT§ T and 3) result from:

pT m ag + A ₁ T ₅ + _{& 2} Β, (38)

and it can be assumed that the relationships between pX pB _t T and D are expressed by the same formula.

pT - b ₀ + ^ Τ _ρ + b ₂ (1 / F) + b ₃ T _p ² + b ₄ (1 / J?) ² + b ^ d / JT), (39) where D «1 / ϊ and pT is equivalent to ρ in equation 23 for the determination of the zinc loss in the slag.

00S8 17/1250

To determine the maximum zinc excretion, no general Expenses, no wages, power requirements, no operating costs, etc. have been taken into account, rather here is only of the "raw materials brought into the furnace and the received products, whereby it only comes down to the two most important products zinc and lead, although later it was Perhaps it could prove necessary in the mathematical puncture to include other components, such as copper, cadmium and precious metals to include «This function, its complete · derivation is not reproduced here, has the following final form:

+ b _o 3) + b ^ P + I) ₃ PTp + b ^ ² +

V -

Here EL is the zinc precipitation and V is a constant, the other symbols result from the above *

The maximum value of the zinc excretion is maintained by continuously calculating the values for various intermediate levels of i ¹ and T with the help of equations 23 and | 8 ^ in which the coefficients are constantly updated to the latest state of the system values determined.

To determine the swish values for D and T , the increase technique is used, which results from an average of four junction values, which are calculated in advance in different pole times, the maximum value Zinc loss in the slag

009817/1250

Conversion of the static model into a dynamic model

For precise predetermination of the furnace output, the individual equations also contain quantities that change the- » Take into account the dynamic mode of operation of the system · Already the inclusion of all previous values of the plant would require a very extensive computer system in order to: t> e- » evaluate the loaded mean values of the independent variables. When determining the value of a dependent change. Earlier values of the same are also not taken into account, cUh "the respective existing value is used without taking into account" ti guns of previous fluctuations in value determined · Although in some cases changes in value are included in a larger one Accuracy »would require a greatly enlarged computer system to achieve the maximum value for the zinc yield to calculate in advance "

009817/1250

Claims (1)

PAXBNXANSPBUCHE 1. Terfair for the operation of a zinc / lead shaft furnace, characterized by continuous monitoring and determination the values for a) the zinc / carbon ratio in the batch, b) the preheating temperature of the combustion air, e) the ratio of slag formers to carbon in the batch, d) the composition of those emerging from the furnace Gases, e) the zinc content of the slag and f) the temperature of the liquid slag emerging from the furnace and in setting the zinc / carbon ratio in the charge as well as the preheating temperature of the combustion air for a maximum zinc excretion based on the relationship: β (E _m ) -V- where B «zinc excretion» V - a constant " S _E - weight ratio of slag formers to zinc in the batch " 5 zinc / carbon ratio in the batch, K * ■ a constant, ρ + 1 ■ the number of carbon moles burned each Oxygen atom of the combustion air, T_ * the preheating temperature of the combustion air, ~ Dq - b ^ and 8q - ac are polynomial coefficients * 009817/1250 1928549 ~ 20 - 2 · procedure, according to. Claim 1 »characterized in that Maximum values β OO for various intermediate values for E and Q? are calculated in advance on the basis of equations 23 and 38, in which the coefficients are continuously updated to the latest status of the measured operating values, and intermediate values for D and T are determined to calculate a maximum average value from the corresponding individual values according to the Function equation for θ 009 8 17/1250 Blank page