DE1907204A1 - Process for the pyrometallurgical treatment of sulfidic iron ores or iron ore concentrates - Google Patents

Description

METALLGESELLSCHAPT Frankfurt / Main, February 12, 1969

Aktiengesellschaft DrOz / GKp

Deutsche Babcock & Wilcox-Dampfkessel-Werke AG

Prov. No. 6122

Process for pyrometallurgical treatment of sulfidic iron ores or iron ore concentrates

The invention relates to a method for the pyrometallurgical treatment of sulfidic iron ores or iron ore concentrates by means of oxygen-rich gases.

A large number of proposals have been made for the processing of sulphidic iron ores or iron ore concentrates have been submitted, which make use of a wide variety of procedural categories. Stand in the foreground Roasting processes that are carried out in deck ovens or one or two-stage fluidized bed ovens and which are too Sulfur dioxide and iron oxide lead (see e.g. German patents 1 123 686, 938 54-4, 1 024 493, 1 046 and 1 132 942).

Another group of processes uses flotation pyrites with preheated air according to the equation

FeS ₂ + O ₂ -> r FeS + SO ₂

or with hot, oxygen-free burner exhaust gases the equation

2 FeS ₂ _ », 2 FeS + S ₂

implemented. The melt containing the iron, in the present case the iron stone, is optionally freed from black powder and processed further in a subsequent treatment (German patent specification 886 390, DAS 1 205 503).

00988 4/0990

In recent times, the cyclone firing systems commonly used in firing technology have found their way into non-ferrous metallurgy and have gained importance for processing copper and polymetallic concentrates (cf. IAOnajew, "Zyklonschmelzen von Kupfer- und Polymetallischenzentraten ¹¹ , Neue Hütte J [O (1965) p. 210). In the cyclone chambers used for so-called cyclone melting, air is blown in at high speed tangentially so that a rotating vortex is created. The fuel or ore concentrate particles introduced into the cyclone chamber are caught by the vortex, burned or melted and thrown against the wall. Bas The melt product that formed reached the collection hearth, in which stone is separated from slag. The reaction gases are processed in the usual way, for example for the production of sulfuric acid.

In connection with an epesially designed cyclone chamber for the pyrometallurgical treatment of comminuted ores, ore concentrates and the like, it is proposed that ores or ore concentrates be coarse or fine Split fractions at different points in the cyclone chamber (BAS 1 161 033). Badurch are supposed to Yield in the form of the melt is greater and the fuels and ores supplied can be ignited very well.

It has now been found that the cyclone chambers known in combustion technology and in the metallurgy of non-ferrous metals for the pyrometallurgical treatment of sulfidic iron ores or iron ore concentrates by means of gases containing oxygen to form a melt containing the iron, sulfur dioxide and optionally volatile non-ferrous metals or IE metal compounds are suitable according to the invention when the iron ores or Eiaenerzkonsentrate to at Semperaturen of at least 1100 ⁰ C. several places

009884/0990

OFUGJNAL INSPECTED

each in the direction of a tangent or secant in a with water evaporation at a pressure of at least 10 atm, cooled cyclone chamber 5 with an approximately horizontal axis

and
introduced / implemented with oxygen-rich gases and with little or no addition of fuel.

Suitable oxygen-rich gases are those with at least 3 ^c / o _t, preferably those with 40-60% oxygen content.

The cyclone chamber having a horizontal or approximately horizontal axis, ie with an inclination to the horizontal of up to 30 ⁰ C, is that the melt products possess a very high residence time in the reaction space to a vertically disposed cyclone chamber advantage. Due to the high gas velocities of the order of magnitude of 100 m / sec and above prevailing in the cyclone chamber, the melt products move as thin films in constant contact with the hot gases along the walls of the cyclone until the end of the reaction.

Feeding through several gas and material feed openings makes the cyclone karamer better adaptable with variable metallurgical properties of pyrite and has a significant influence on their heat conversion rates.

The melting temperatures are largely determined by the composition of the stone produced. Depending on the predetermined ratio of pyrite and oxygen can either melting a pure FeS stone with sulfur contents of about 35 $> S having a melting point of about 1150 - has 1180 ⁰ C, or is produced FeS-calcination to by partial FeO a stone containing less sulfur. If necessary - especially when pure ore concentrates are present - the conversion can be driven up to FeO with a melting point of 1380 ^° C.

00988W0990

In certain metallurgical processes in which a stone with a low FeO content is produced, it can lead to Avoidance of iron losses resulting from gait components forming slag be advantageous to cover the heat demand, small amounts of additional fuel, preferably residue-free fuels, via the tangential feed openings or the cyclone tip to feed.

The already low fuel supply is completely eliminated if the amount of oxygen is measured in such a way that noticeable proportions, preferably 10-30 #, of the primary stone formed are roasted to FeO.Since FeS and FeO are miscible and form a low-melting eutectic, the melting temperature of the stone can and thus the necessary cyclone temperature can be reduced. The oxygen demand can also be reduced. At an average Zyklontenperatur of about 200 ⁰ C above the melting point of the stone and a melting temperature of FeS / FeO eutectic of about 920 ⁰ C, the cyclone chamber results in a lower applicable temperature such of 1100 ⁰ C.

Are heavier volatilizable constituents of the pyrite, such as zinc, are separated, so it is recommended to drive the cyclone temperature as high as möglieh, that is in and of themselves low cyclone temperature by higher .Sauerstoffzugabe to values of greater than 1300 ⁰ C, preferably to 1500 - 1600 ⁰ C, to increase.

The desired oxygen concentrations are - if not already oxygen-rich gases are available through Mixing air and technically pure oxygen produced. The oxygen concentration can can also be created by supplying oxygen and air to the cyclone chamber separately. The last

009884/0990

The mentioned working method is particularly recommended, when 70 # oxygen that can be produced cheaply is available.

FeS / FeO melts attack Al ₂ O or SiOg-containing linings very strongly, since AlpO. Or SiOp is soluble in PeO. Cyclone melting can therefore not be carried out in conventional ovens without great masonry wear and tear occurring in a short period of time. By designing the reactor walls as steam-cooled, pinned pipe walls lined with rammed earth, natural protection can be achieved by freezing a thin layer of solidified melt products. This is only possible with intensive cooling, as is the case with steam cooling for special

fish heat transfer of more than 40,000 kcal / hm is to be achieved.

In order not to fall below the acid dew point in the event of local formation of sulfur trioxide, the lower vapor pressure is around 10 atmospheres, with wall temperatures of around 180 ^° C. being obtained. In order to avoid attack by the sulfur iron on the pinning of the pipe walls, it is advisable not to let the vapor pressure rise above 100 atmospheres, with wall temperatures of approx. 320 ^° C. being established.

The volatilization of metal compounds in the melting cyclone increases with increasing temperature. Optimal for this purpose, eg for Zinkverflüchtigung, temperatures of over 1300 ⁰ C, which can only be achieved in steam cooled cyclone chambers at a reasonable cost. Temperatures of 16OO ° C can be achieved when using gases with approx. 55 ° h oxygen. It succeeds in the volatilization of zinc to values above 90 _% of arsenic and lead

009884/0990 .. - ⁶ -

Drift values over $ 95>. Silver, cadmium, rhenium, selenium, tellurium, germanium, antimony, vismuth and others can be volatilized just as easily.

Together with the high heat conversion rates of over 2. 10 kcal / m h, the excellent heat and mass transfer behavior with extremely short dwell times brings the Work with the described cyclone chamber in combination with a downstream air trap, which the gas after a U-shaped deflection flows through, a high dust binding ™ degree and low proportions of mechanical plug dust in the exhaust gas. After cooling the gases in a boiler, preferably consists of an empty shaft formed from pipe walls and a subsequently horizontally flown through boiler, the volatile substances accumulate in the subsequent dust separators in quantities that are theoretically achievable Come close to worth. A small partial flow of the oxygen-containing secondary flow is either just before or added shortly after the cooling grate for post-combustion of the sulfur contained in the exhaust gases. As a dust collector Electrostatic precipitators and bag filters come into consideration.

The method described brings surprisingly in addition to excellent thermal and economic benefits, major improvements in the purification of Pyrite of constituents which are undesirable for the steel industry and which can make the burn unsaleable. Through the thermal processing in the melting cyclone to high-purity stone, high-percentage concentrate of the volatilized Components, high percentage SOp gas greater than 30 # SO «and slag can be increased four times of the burn-up, which cannot be achieved with the use of mechanical processing with conventional methods are. The amount of steam generated improves noticeably

009884/0990 _

the economics of the process.

Fig. 1 shows a flow diagram of the process according to the invention represent.

Fig. 2 shows the melting cyclone, the hearth and the entrance to the waste heat boiler in the manner of an enlarged section Fig. 1 again.

The dried and possibly regrinded pyrite is fed from a feed hopper 1 via a belt weigher 2 into an air stream that is directly preheated in a combustion chamber 3 and is blown as primary air stream 4 along a secant into the melting cyclone 5, which has evaporative cooling tube walls 17. The heating of the primary air flow, which can also take place indirectly with the waste heat of the process, should not be driven above the ignition point of the pyrite. The optimal preheating of the primary air stream is slightly below the ignition point, conveniently at about 400 ⁰ C. The also preheated in the same (or a higher) temperature secondary air 6 is a Säuerstoffleitung 7 enriched nit oxygen and fed through a line 20 through. Gases of any origin with an acid content of more than 60 pounds can be used for adding oxygen. If necessary, additional fuel can be fed into the melting cyclone 5 either via the secondary air line 20 or via the cyclone tip 19.

Ib melting cyclone finds the splitting and rapid reaction the equations

FeS ₂ ^ FeS + S and S + O ₂

009884/0990

which in part from the side reaction

PeS ₂ + 2 1/2 O ₂ 1 PeO + 2 SO ₂

can be accompanied instead.

The stone formed in the cyclone 5 runs together with the slag formed into a hearth 10 in which to separate A sufficient dwell time, preferably greater than 1 hour, is provided for stone and slag. In one With an appropriate configuration R, further metallurgical processes can also be carried out of such a hearth.

The heat demand of the stove can, if necessary, be covered by blowing oxygen through a lance 11.

The resulting stone is, e.g. in a water channel 12, granulated in a known manner for further treatment, e.g. fluidized bed roasting.

The gases containing sulfur dioxide exiting from the melting cyclone 5, after being deflected by a baffle wall 18, flow through a guillotine 8, which catches a large part of any stone droplets that may be carried along, and W pass into the waste heat boiler 9 for cooling lost volatile substances, e.g. dusts containing non-ferrous metals, are deposited. The dust precipitated in the horizontal part of the waste heat boiler 9 can be returned to the feed hopper 1 via 15. Concentrates rich in non-ferrous metals are drawn off via line 16.

009884/0990

example 1

From a feed hopper 1 2 tons to a moisture content <0.5 i ° dried pyrite having a grain size of from 50 ° to / o greater than 90, where M in the task line 4 of a melting cyclone 5 hour via a weigh feeder. 2 The pyrite had the following composition:

PeS ₂ 90 $>

ZnS $ 3.8>

PbS $ 0.9>

As ₂ S ₅ 0.3 #

Gait 5 f °

In the feed line system 4, which is divided into four streams, the pyrite is ^{conveyed to the melting cyclone 5 at a total of 300 Nm / h in the combustion chamber 3, preheated to 400 °} C., and blown into it along the cylinder jacket via four openings along a secant. 450 Nm / h, also ^{preheated to 40O 0} O air are mixed together in the secondary flow line 6 with 280 Nm / h oxygen (approx. 98 $ O ₂ ) from a cold gasifier via the line 7 and blown tangentially through separate openings into the melting cyclone. The melting cyclone 5 inclined at 10 ° to the horizontal has a clear diameter of approx. 500 mm and a length of the cylindrical jacket of approx. 700 mm.

The cyclone shell consists of pinned pipe walls 17, which are clad with rammed earth and which are produced by water evaporation be cooled at 15 atü.

From the melting cyclone through the cyclone neck 990 NmVh about 40 jSiges SO ₂ gas, loaded with the volatilized non-ferrous metal compounds and entrained slag droplets emerge. The temperature of the gas flow is approx. 1500 ° 0.

009884/0990 - 10 -

Through the slag discharge hole 13 formed in the melting cyclone of the stone also passes together with the slag at a temperature of close to ⁰ 150o C in a stove at 10. After settling for about one hour, about 120 kg / h of FeO-containing slag can be separated off. An addition of flux is not necessary because of the high temperature. Every hour, 1250 kg of a pure stone with a sulfur content of $ 30, which contains less than 0.2 ° J> Zn, 0.07 i> Pb and 0.02 # As.

The SOp gas emerging from the melting cyclone, after being deflected at a baffle 18, combines with the SOg gases created by the occasional addition of oxygen in the hearth and flows through the catching grate 8, which is formed from pipes, in which a large part of the stone drops that are carried along are collected. In the waste heat recovery boiler 9, the SO ₂ gases are cooled to 300 ⁰ C, wherein including the accumulating in the cyclone jacket steam amount is about apply 950 kg / h of saturated steam at 15 atm. The small amount of dust of approx. 50 kg / h that occurs in the horizontal part of the waste heat boiler 9 is returned to the feed hopper 1. In the hot electrostatic precipitator 14 falls 100 kg / h at an HE-metal-rich dust containing the volatilized compounds in concentrations of 49.5 fi Zn, 14.9 # Pb and 3.5 x $> ATF. The dust can be smelted to extract the non-ferrous metals.

Example 2

From a feed bunker 1, 1.9 t / h of a flotation pyrite of <1 # moisture with a grain size 30 i " greater than 90 / *" are fed into the feed line 4 of a melting cyclone 5, which has the same dimensions as in Example 1 possesses and operates with the same vapor pressure. The pyrite has the following content

009884/0990 - 11 -

ORIGINAL INSPECTED

PeS ₂ 95 , 5 ZnS 2 ,1 PbS O fO As ₂ S ₃ O gait 2

In the feed system divided into four streams, the pyrite is conveyed with a total of 350 NmVh of ^{air preheated to 40O 0} C to the melting cyclone 5 and blown tangentially into it. 300 Nm / h of air, preheated in the combustion chamber 3 by natural gas combustion to 600 ⁰ C, are mixed in the secondary flow line 6 with 360 Nm / h of 75 $ igen from an air cereal plant and supplied via the line 7 and tangentially into the through four openings Melt cyclone 5 blown in.

To obtain a FeS-Stein almost theoretical composition 50 Nm / h of methane are fed via the cyclone tip 19 as an auxiliary heating to cover the required at 1400 ⁰ C Zyklontemperntur heat requirements. The gases leaving the Schraelz cyclone in an amount of 1060 Nm / h have an SOp concentration of approx. 30 pounds.

The FeS stone flowing out of the melting cyclone 5 is collected in a hearth 10, which allows it to stay for about two hours. The bath is prevented from cooling down by blowing oxygen through the lance 11. There are 1300 kg / h of a PeS stone with 35? Ί S, which is practically free of zinc, lead ( $ 0.05>) and arsenic (0.008 5i). After granulation in water, it is an excellent starting material for the production of a pure burn through roasting.

- 12 009 884/0990

After cooling the SOg gases with steam generation in the waste heat boiler 9, approx. 75 kg / h of a non-ferrous metal concentrate with 39 ° Zn, 12.5 ° Pb and 1.7 Ί » As are obtained in the dust filter.

009884/0990 - 13 -

ORiQJNAL INSPECTED

Claims (7)

PATENT CLAIMS 1.) Process for the pyrometallurgical treatment of sulfidic iron ores or iron ore concentrates by means of oxygen-containing gases with the formation of a melt containing the iron, sulfur dioxide and optionally volatile non-ferrous metals or non-ferrous metal compounds at temperatures of at least 110O ⁰ C, characterized in that the iron ores or Iron ore concentrates are introduced at several points in the direction of a tangent or secant into a cyclone chamber (5) cooled with water evaporation at a pressure of at least 10 atm with an approximately horizontal axis and converted with acidic gases and with little or no addition of fuel. 2.) The method according to claim 1, characterized in that the iron ores or iron ore concentrates at temperatures above 130O ⁰ C, preferably at temperatures in the range of 1500-160O ⁰ C, are implemented. 3.) The method according to claim 1 or 2, characterized in that the iron ores or iron ore concentrates are reacted with oxygen-rich gases whose Op content is at least 30 #, preferably 40-60 $> _t . 4.) Method according to claim 2 or 3t, characterized in that that the iron ores or iron ore concentrates with formed from any gases and technical oxygen oxygen-rich gases are implemented. 5.) The method according to claim 1, characterized in that the fuel to be added if necessary is introduced via the cyclone tip (19) or via the line (20) will. 009884/0990 - 14 - 6.) Method according to claim 1, 2 ^ 3 or 4 »characterized ι that the iron ores or Eisanerz concentrate with the formation of an FeO / FeS mixture existing melt is implemented. 7.) Method according to claim 1, 2, 3 or 4, characterized in that that the iron ores or iron ore concentrates with the formation of a melt consisting of PeO implemented. 009884/0990 Blank page