DE2063577C3 - Process for the production of a reduced preliminary product for ferronickel production - Google Patents

Description

The invention relates to a method for producing a reduced preliminary product for: Ferronickel production from nicke! oxidha! tigerr. iron-rich starting material and nickel magnesium silicate ore, wherein the nickel magnesium silicate: crushed and calcined will.

Nickel is a metal that; for the production of stainless steel and for the production of heat-resistant Alloys is indispensable With increasing nickel consumption, the availability of nickel-rich ores appears gradually decreasing, so that there is an increasing need for processes for the processing of nickel from comparatively low-nickel ores, for example from laterite with a high iron content (see Table 1) A number of processes for processing iron-rich nickel ores have already been investigated been. Thus, according to US-PS 27 67 075 oxidic ores containing nickel and iron oxides, treated with silica and the mixture obtained is subjected to a controlled reduction. From the A number of such processes are to be emphasized as those which aim at a preferred reduction of nickel build from the ore. For example, from GB-PS 9 60 701, iron-rich, nickel-containing Ore that contains free and bound water under an adequate reducing atmosphere too calcine.

This preferred reduction in nickel is based on the differences in thermodynamic properties of nickel and iron, especially the greater affinity of iron for oxygen in the Comparison to the affinity of nickel for oxygen. In the practical implementation of the refining by Reduction of iron-rich nickel ores such as laterite, however, become iron and nickel at the same time In fact, reducing nickel in preference to reducing iron has proven to be extremely difficult in practice proven. When iron-rich nickel ores are reduced in a set atmosphere, in Usually iron and nickel are formed at the same time by the reduction so that the resulting Ferronickel has a relatively low nickel content An increase in the nickel content in ferronickel through follow-up treatments has proven extremely difficult.

The object of the invention is accordingly to provide a method for processing iron-rich nickel ore or to indicate of high ferrous nickel oxide, through which the difficulties outlined above and problems are eliminated.

According to the invention it has now been found that the iron contained in iron-rich nickel ores is in the form of Difficult to reducible fayalite can be masked, so that due to the different reducibility fayalite and the nickel compound nickel can be selectively reduced.

By adding SiO ₂ , the formation of fayalite can consequently be brought about in a targeted and deliberate manner, whereas, in contrast to this, the formation of fayalite was always carefully avoided in the conventional methods of iron processing.

The formation and decay of fayalite (2 FeO SiO ₂ ) can be represented by the following chemical formulas:

2 Fe ₃ O ₄ + 3 SiO ₂ 3 (2FeO SiO ₂ ) 2 FeO · SiO ₂
2 Fe + SiO ₂

(1)

(2)

The formation of fayalite according to equation (1) takes place in a CO / CO ₂ atmosphere with the composition CO / (CO + CO ₂ ) Sl, 6%, during the

Disintegration of the fayalite according to equation (2) takes place only at a CO content of more than 90% when the iron in nickeler ι so according to Equation (1) is fixed as fayalite, the nickel can be selectively reduced without the fixed iron attacked reductively will.

The method of the type mentioned at the beginning is therefore characterized according to the invention in that the calcination is ^{carried out at 500 to 800 0} C, that the calcined ore is slurried in water and carbon dioxide-containing gas is forced into the slurry with a COr partial pressure of at least 1 atm. that the slurry is separated by filtration into a magnesium-rich filtrate and a silicon dioxide-containing residue, that magnesium carbonate is precipitated by heating from the filtrate and then decomposed to MgO and CO2, that the silicon dioxide-containing residue is mixed to the iron-rich starting material and that the mixture in a CO / CCVAtmosphäre of the composition 1% <CO / (CO + C0 ₂ ) <90% is heated to sufficient temperatures for the formation of fayalite and solid solutions of fayalite and forsterite.

It is useful here to remove the exhaust gas from the last heating stage, i. H. the reduction stage, as a carbon

Table 1

15 to use dioxide-containing gas to fluidize the slurry. According to the invention, latent or garnierite is preferably used as the iron-rich starting material and as the nickel-magnesium silicate ore, the nickel-magnesium silicate ore expediently being broken down to a grain size of finer than 0.25 mm. The slurry should be made from 8 to 50 parts by weight of water and 1 part by weight of calcined ore. It is also advantageous to carry out the turbulence and the filtration with the carbon dioxide-containing gas under pressure and to expose the filtrate to atmospheric pressure in order to precipitate the magnesium carbonate. To precipitate the magnesium carbonate, the filtrate can be heated to the boil. In addition, coke can be added to the mixture of residue containing silicon dioxide and iron-rich starting material as an additional reducing agent, and it can also be expedient to heat the mixture in an atmosphere containing argon.

_{Nickel ores with a high SiO 2} content, such as, for example, garnierite (cf. Table 1), can be used as SiO ₂ source for the method according to the invention.

Chemical composition (%)

SiO,

Fe

CaO

MgO

Ni

Al ₂ O ₃

Cr ₂ O ₃

Garnierite 35-50 9.0-15 0.1-0.3 20-30 > 2.0 0.5-1.0 0.5-1.5 Latent <5 > 40 <0.5 <5 > 0.5 3–10 > 2

However, most high-silica nickel ores contain larger amounts of magnesium oxide, for example 20 to 30% magnesium oxide in the case of garnierite (see Table 1). The chemical behavior of the Magnesium oxide contained in nickel ore is similar to that of nickel oxide in wet processing processes. As a result, the presence of magnesium oxide is undesirable in wet nickel recovery processes They also interfere in dry preparation processes, for example in the Krupp-Renn process larger amounts of magnesium oxide.

As already mentioned, in the method according to the invention, that in the nickel magnesium silicate ore Magnesium oxide contained extracted with the help of carbon dioxide and after the magnesium oxide extraction remaining residue as a source of silicon dioxide for the formation of fayalite in the refining process of the iron-rich Nickel ores used The nickel processing method according to the invention has the following advantages:

1. The reduction of nickel in iron-rich nickel ore and in the residue of the magnesium oxide separation from the nickel magnesium silicate ore is accelerated

2. That in the exhaust gas of the reduction of both the iron-rich nickel ore and the residue after the Carbon dioxide contained in the nickel magnesium silicate ore can lead to the separation of magnesium oxide Extraction of the magnesium oxide from the nickel magnesium silicate ore can be used, which significantly improves the overall energy balance of the process.

An important feature of the invention is that the usually discarded magnesium of the nickel magnesium silicate ore, for example gamierite, for useful further use in the form of magnesium oxide is extracted. Since the magnesium oxide extracted in this way has a certain commercial value represents, the economics of the entire nickel processing process from iron-rich nickel ores can be significantly improved by removing the residue from the magnesium oxide extraction as Silica source for the formation of fayalite from the iron compounds contained in the iron-rich ores can be used, whereby the fayalite suppresses the reduction of iron ions to iron.

In the method of the invention, it is necessary for the preferential reduction of nickel that the Solid ore in a mildly reducing atmosphere of the nature indicated above is treated. When the starting material melts, the activity of the individual molecules of the Ore too big to prevent fayalite from forming. In theory it can be used to carry out the preferred Any furnace that has an accurate setting and reduction of nickel can be used Control of the atmosphere ensures, for example, a multi-stage calcining furnace, with a calcining furnace Purge gas device, a melting furnace or a rotary drum furnace.

Accordingly, the products of the reduction process according to the invention fall from furnace types like them indicated above, in the form of lobes or spongy particles. In these reduction products, the fayalite and fayalite forsterite are in shape Solid solutions included and form the slag component of the products. This slag compo-

nente is obtained in a mixture with the desired nickel or ferronickel, so that the metallic components separated from the slag in a conventional manner.

For a better understanding of the invention is in the following in conjunction with the drawings Embodiment of the invention described. It shows

F i g. 1 is a flow chart of one embodiment of the nickel recovery process according to the invention;

2 shows the yield in a graph Magnesium oxide as a function of calcining conditions,

3 shows the yield in a graph Magnesium oxide as a function of the concentration of the calcined ore in the slurry,

4 shows a graph of the yield of i _S magnesium oxide as a function of the CO ₂ partial pressure in the gas which is pressed into the slurry of the calcined nickel magnesium silicate ore for fluidization,

Fig. 5 shows an equilibrium diagram for the reduction reactions in the system Fe - SiO ₂ - C - O2,

Fig. 6 graphically shows the degree of reduction as a function of the reduction temperature for the Method according to the invention,

7 shows an X-ray diffraction diagram of a fayalite,

F i g. 8 is an X-ray diffraction diagram of the reaction products obtained according to one embodiment of the invention;

9 shows the degree of reduction in a graphic representation of nickel and iron as a function of the reduction temperature,

10 is an X-ray diffraction diagram of the according to a further embodiment of the process according to the invention obtained reaction product.

The principles of the present invention are illustrated below with the aid of the equilibrium diagram of the reduction reactions in the Fe — SiO ₂ —CO _{2 system} , an iron ore reduction system, shown in FIG. Laterite and garnierite contain iron in the form of limonite (Fe ₂ O ₃ · η H ₂ O). The limonite gives off its water of crystallization between 300 and 350 ^° C. and changes into iron (IIl) oxide. The Fe ₂ O ₃ can easily be reduced _{to Fe 3} O ₄ according to the scheme indicated in formula (3). The CO content of the reduction atmosphere can be low for this reduction.

3 Fe ₂ O ₃ + CO
2Fc ₃ O ₄ + CO ₂

(3)

The equilibrium of this reduction is shown in FIG. 5 represented by the curve AA '.

In the presence of silicon dioxide, the Fe ₃ O ₄ thus formed reacts with the SiO ₂ to form fayalite (2 FeO · SiO ₂ ) in accordance with equation (4). The equilibrium curve of this reaction is identified in FIG. 5 with B-β '.

2Fc ₃ O ₄ + 3SiO ₂ + 2CO
► 3 (2 FcO ■ SiO ₂ ) + 2 CO ₂

(4)

The minimum content of CO in the reducing atmosphere required for the formation of fayalite is a maximum of 1.6% _{in the f, s} temperature range from 400 to 140O ^{0 C.} The fayalite can be easily obtained without adjusting the reducing atmosphere more precisely.

If, however, there is not enough SiO _{2 available for the reduction according to equation (4), the Fe 3} O ₄ formed according to equation (3) is further reduced to Fe or FeO, as shown in FIG. 5 is indicated by the equilibrium curve CCD. The further reduction of FeO to Fe is shown in FIG. 5 represented by the equilibrium curve CE .

On the other hand, the _{fayalite formed in the presence of SiO 2} and comparatively low CO contents can only be further reduced when the CO content in the reduction atmosphere is much higher than the CO content required to reduce the iron oxides. The reduction of fayalite to Fe only occurs when the CO content in the reduced atmosphere is 90% or more, as indicated in Fig. 5 by the equilibrium curve F-F '.

In numerous investigations it was also ensured that no nickel olivine (2 NiO · SiO ₂ ) is formed during the reduction according to the invention. This is apparently due to the fact that in the case of iron-rich nickel ores, such as laterite, the reduced metallic nickel tends to melt in the metallic iron and the activity of the nickel in the reducing system is reduced to such an extent that despite the presence of SiO ₂ no nickel olivine is formed. When using the silicon oxide-containing residue obtained from the nickel-magnesium silicate ore, the crystal structure of the residue is broken up by the formation of fayalite, so that the reduction of the nickel is accelerated.

The carbon monoxide content required for fayalite formation in the reducing atmosphere is as in Fig. 5 shown between 1% and 90%. This wide CO concentration range is for practical use It is important to practice the present invention. The operation of the Reduction furnace and the setting of the reducing atmosphere are significantly simplified. As a reducing agent A wide variety of substances can be used in the solid, liquid or gaseous phase, for example Coke, coal, anthracite, hydrocarbon gas, carbon monoxide and the like.

The proportion of carbon monoxide in the reducing atmosphere, which according to the invention is required to reduce the nickel, should be above the equilibrium curve BB "\ nFig. 5. Theoretically, this concentration range for carbon monoxide is below the lower CO concentration limit for the fayalite Formation in a reducing atmosphere, so that the fayalite formation can be achieved without difficulty. The SiO ₂ to be used according to the invention for masking the iron in laterite can be either pure SiO ₂ or ores containing silicon _{oxide. Natural SiO 2} and sea sand are used for this purpose frequently used.

The silicate ores that can be used as SiO ₂ source according to the invention for masking iron can sometimes contain magnesium oxide. This MgO reacts with SiO ₂ to form forsterite, a compound that is similar in composition to that of Fayali. The forsterite formed can form solid solutions with fayalite, which are known as forsterite-fayalite.If magnesium oxide is present in the aggregate that provides silicon oxide, fayalite is not formed as a simple compound, but as a rule as a solid solution of forsterite-fayalite.

In principle, any other starting material besides latent can be used as starting material for the process according to the invention iron-rich nickel ore can be used, such as garnierite, or any nickel oxide with a greater iron content, even if these compounds are not in the form of ores.

As explained above, one of the important features of the invention is its use of nickel magnesium silicate ore, for example of garnierite, after separation of the magnesium oxide as Silica-supplying aggregate. This method is in the flow chart of FIG. 1 and below described in more detail. The ore used as silica surcharge, for example the garnierite, is initially broken down to a grain size that is suitable for the subsequent calcination stage and in usually 0.25 mm or finer.

The thus-crushed ore is calcined at 500 to 800 ⁰ C to remove the crystal water and to separate the MgO Gangartkomponente by decomposition of the crystal structure of the magnesium silicate. A slurry was prepared by adding 8 to 50 parts by weight of water to each part by weight of the calcined ore. This slurry is whirled up in a slurry tank at 20 to 50 ^° C. for 0.5 to 3 hours by injecting carbon dioxide-containing gas or by blowing in pure carbon dioxide at pressures of 1 to approx. 20 atm. The magnesium oxide isolated in the calcined ore is dissolved according to the formula (5):

MgO + 2CO ₂ + H ₂ O
Mg ²⁺ + 2 HCOj-

(5)

The thus fluidized slurry is pressure filtered. The filtrate is either suddenly exposed to atmospheric pressure or heated to boiling, so that the magnesium is precipitated as magnesium carbonate MgCO ₃ · 3 H _{2 O while degassing the dissolved CO 2.}

The operating conditions for the above-described separation of the magnesium oxide from the initial nickel magnesium silicate ore are further described below. The source ore is preferably, as already mentioned above, on one

ίο grain size of about 0.25 mm crushed so as to the subsequent calcination and extraction to facilitate.

The purpose of the calcination process is the thermal decomposition of the ore in preparation for separation of the MgO. Both MgO and nickel oxide are present in the ore in the form of solid solutions with the silicate, by calcining the MgO into an easily extractable form and the NiO into an easily extractable form reducible form are transferred.

The decomposition temperature for the crystals of the nickel magnesium silicate ore , which contain the MgO in the form of water-containing silicates, is approx. 500 to 600 ^° C. The minimum temperature for the calcination must accordingly be regarded as ^{500 ° C.} _{The MgO and SiO 2} separated in this way from the crystal of the nickel magnesium silicate ore recombines easily over 800 ^° C. to form the very stable forsterite (2 MgO · SiO ₂ ). Accordingly, the calcination temperature below 800 ⁰ C should be maintained, that is, the suitable temperature range for this calcination is 500 to 800 ° C.

In Fig. 2 shows the relationships between the MgO yield and the calcining time for various calcining temperatures. The percentage yield is defined as the ratio of the _{amount of MgO extracted in the form of MgCO 3} 3 H ₂ O to the amount of MgO originally present in the starting ore:

Yield =

extracted amount of MgO

amount of MgO originally present in the ore

-100 {»/").

The relationships shown in Fig. 2 were determined by measuring the yields obtained for various calcining times with the other conditions such as the concentration of the slurry and the CO ₂ partial pressure being kept constant. The yields are plotted on the ordinate and the calcination time on the abscissa.

From the representations of FIG. 2 shows that when the calcining time is about 1 hour, can be achieved than 30% of the yield of MgO more when the calcination temperature between 600 and 700 ⁰ C. The highest yield can be obtained when the calcination is two to three hours, carried out at 600 ⁰ C s. ₅

To the ore thus calcined, water is added to make a slurry. The concentration of the ore in this slurry should preferably be low, since the solubility of the magnesium hydrogen carbonate to be produced in the following stage is only about 0.64 g / 100 ml H ₂ O at 35 ° C. under normal pressure. To determine the industrially meaningful range of the concentration of the slurry, the MgO yields for <><, various concentrations of the calcined ore were determined in test experiments. The water content of the slurry was varied between 1 and 40 parts by weight per 1 part by weight of calcined ore. The treatment with CO ₂ was carried out by blowing in the gas with a throughput of 2 l / min at 35 ^° C. and normal pressure over the slurry. The results are shown in curve PP ' in FIG. 3 reproduced. The ordinate in FIG. 3 there, as in FIG. 2, the yield of MgO again, while the weight ratio of water to solids is plotted on the abscissa.

The curve PP ' in FIG. 3 it can be seen that the yield of magnesium oxide becomes greater than 30% if more than 8 parts by weight of water are added to 1 part by weight of ene. To test the effect of more dilution of the slurries, different slurry concentrations were made by adding 8 to 100 parts by weight of water to 1 part by weight of ore. The yield a magnesium oxide has been long by 3 hours Einbla sen of CO ₂ gas at a rate of 2 l / min be a reaction temperature of 35 ⁰ C and a reaction pressure of 5 kg / cm ^{2 is} obtained. The results are shown in the curve Q-Q'm F i g. 3 reproduced.

From the curves PP ' and QQ' in FIG. 3 it can be seen that the appropriate concentration of calcined ore in the slurry is 8 to 50 parts by weight of water per 1 part by weight of ore, assuming a reasonable duration of the conversion

■ KWfiM / 1 '

wetting with CO ₂ of 1 to 2 hours If the water content is less than 8 parts by weight per 1 part by weight of ore, the MgO yield is too low, while at water levels higher than 50 parts by weight per 1 Gewichtstei'l ore yield s no longer can be improved, although the devices must be enlarged due to the larger amounts of water.

The slurry of the calcined ore is subjected to _{a treatment with CO 2 ι ο in a slurry tank.} For this purpose, CO ₂ or a CO ₂ -containing gas is pressed into the tank so that the chemical reaction takes place according to formula (5). During this CO ₂ treatment, the reaction rate becomes too slow if the reaction temperature is too low. At too high, ₅ reaction temperature on the other hand, the solubility of CO ₂ is reduced in water in an unfavorable manner. For a reasonable duration of the injection of CO ₂ and with reasonable operating pressures, for example when introducing one hour under atmospheric pressure, the preferred temperature range is between 20 and 50 ° C.

The pressure of the CO ₂ or the CO ₂ partial pressure of the COr-containing gas should be determined taking into account the solubility of the CO ₂ in water. In general, a high CO ₂ partial pressure increases the solubility of the CO ₂ in water and improves the MgO yield. The influence of the COr partial pressure on the MgO yield was investigated by introducing a COr-containing gas with various CO ₂ partial pressures into the slurry at 50 ° C. for one hour. The slurry was obtained by adding 10 parts by weight of water to 1 part by weight of calcined ore. The partial pressure of the CO ₂ was varied between 1 and 7 atm. The results are shown in FIG. 4 summarized The figure shows that the yield of MgO increases suddenly when the COr partial pressure is increased from 1 atm to 2 atm. For partial pressures above 2 atm, the yield is hardly improved

When filtering the thus treated slurry, it should be taken into account that both the slurry before filtration and the filtrate should be kept at the same pressure level, since a reduction in pressure before filtration leads to a separation of the magnesium dissolved under pressure in the form of MgCO ₃ . 3 H ₂ O, as described above, would occur. Accordingly, partition members are provided in the slurry tank for COi treatment to divide a filtration chamber directly adjacent to the slurry chamber with the slurry. The filtration can be carried out so that both the slurry chamber and the filtration chamber are maintained at the same pressure level. While the residue _S s can remain in the slurry chamber after filtration, the filtrate is discharged from the filtration chamber.

The SiO ₂ content in the residue obtained in this way is significantly higher than the SiO ₂ content of the starting material. For example, some Garnierite ores used in the tests contained 40.62% SiO ₂ and 2.97% (Ni + CO), these contents being increased to 49.45 and 3.75%, respectively, as a result of the removal of magnesium as described above could become. In this way, excellent silica aggregates were obtained, which at the same time served as additional nickel suppliers. In addition, the reducibility of the nickel is improved by the decomposition of the water-containing silicate crystals by the calcination described above

When the external pressure on the filtrate, the Mg ²⁺ ions contains, is changed, for example, by canceling the excess pressure or by boiling, and the remaining CO ₂ is stripped from the filtrate, whereby MgCO ₃ ■ 3 H ₂ O precipitates. MgO can be prepared from these precipitates.

The residue obtained in this way, which is referred to herein as the "silica-containing residue", is This mixture is then mixed with the iron-rich nickel ore or with an iron-rich nickel oxide heated in a reducing atmosphere to a temperature high enough for the formation of fayalite or from solid solutions of fayalite and forsterite to ensure that the reduction of nickel is accelerated while the reduction of iron by the formation of fayalite or by the formation of solid solutions of fayalite and forsterite is suppressed.

The following examples illustrate further details of the invention.

example 1

Nickel magnesium silicate ore, which consisted essentially of garnierite and the chemical composition of which is shown in Table 2, was broken down to a grain size of less than 0.25 mm and calcined at 600 ° C. for 2 hours. A slurry was prepared by adding 200 ml of water per 5 g of the ore calcined in this way, which was then whirled for 2 hours by introducing exhaust gas from the reduction process at a rate of 1 l / min under 5 atm. At the same time the CO _{2 was dissolved} in the slurry. The exhaust: had a temperature of 40 ° C and consisted of 2071 CO ₂ and approx. 80% of N ₂ , with approx. 0.1% CO being contained. The thus fluidized slurry was then filtered under 5 atm. The filtrate was heated to the boil to separate the magnesium in the form of magnesium carbonate.

The MgO yield was 33%.

Table 2

Composition in (icw .- "/ n heat loss SiO ₃

Ix ₂ D ₁ AIjO ₁

CaO

Nit

Ci a in ic lit

10.72

40.62

15.54

Example 2

80% iron-rich nickel ore (latent with the chemical composition shown in Table 3 - 0.60

0.24

27.34

2.97

tongue) and 20% SiO ₂ with a purity of 99.6 ^C were mixed. This mixture was for 1.5 hours in a test oven with three different «

SSÄi ^ Ä- ° " ^co " ^Gehal1 "~

Table 3 _ _. _

Wn Composition in% by weight ^ ^ ^ .. ^ _{0 MgQ}

Heat loss He ^Ni; "" .......

_Laterite , 768 50.45 1-41 3.18 4.18 0.43 1.28

κ, -,, i, ro concentration and the reduction time, were

For comparison, the iron-rich nickel ore with CO Jon; _desse i _ben test furnace as in the

the composition shown in Table 3 in the ^ ^te reduction attempt complied with,

reduced in the same way as described above, provided ^. ^ _different temperatures

only that the reduction in the absence of SiO ₂ ^ wj _reductive functions of the reduction was

was carried out. The remaining reduction conditions ngun-,> ™haben | ^e ™ _{h of the following} equation determines:

genes such as the reduction temperature. ^ gray η

Decrease in oxygen through reduction. ₁₀₀ (%)

^R = 7o7derll ^ i ^^^^ amount of oxygen

7o7derll ^ i ^

,, u / p «» ς Table 4 and F i g. 6 it can be seen clearly,

The degree of reduction R defined in this way corresponds to the ^ '^ * _{h in the} conventional process

commonly used deoxidation ratio. cf ™ _{oxide and the nickel oxides of} the ores at the same time

The formation of fayalite was reduced by X-ray ^ - E. nox.dun * _metallic nickel,

movement diagrams ensured. For this purpose _I ^«1 « before ™ ^ ^ ^ herW> _mhche n

was an X-ray diffraction diagram of a normal _2? ^ b «° ™ e ^^ is _treated , _lie g _en , m

Fayalits recorded separately. The Rontgenbeu ^ process _iron (III) ions and iron (II) ions

Flow diagrams of the test samples were then EndP ^r oduK v ^^ ^ ^. _{m A gsen}

against this standard diagram to demonstrate the more ^ before s _{E. sens} ^ _{metalUschem iron} reduce

Education and the presence of fayalite. " _Order is against, according to the procedure

The conventional method and after., O J ⁰ ™ ^ | _ie ^B _{in Ausga} Eisenoxi contained ngserz

the method according to the invention obtained samples of ^ "J _{during DJE entha} i _requested N.ckelox.

were analyzed. The results of these analyzes are «^ _c ^m _{leunit reduced} ,

summarized in table 4. _Tronically, for each of these samples de bescmeu g ^ ^ _{Gehahe meta "Nicke}

the degree of reduction R defined above was determined J ₆ ^ metallic products of Table 4 out

the results of these determinations in fg6 ο ^^ _{fo restrictive} definition was used:

are summarized.

(metallic njckel)

nickel + metallic iron)

Table 4

Procedure Reasons- - -

^1CmP - GM. Me · »» - '^ * ^K N ^ d Nickel

Reaction composition 1%)

Metal iron ^{l: iscn}

I C)

.. ", 97 47 88 0.48 1.31 0.45

Method according to the invention 800 M - ^ - - · _{4 2 49} 1.33 1.09

¹⁰⁰⁰ "Vn, 0-8 4Ul 0.23 1.41 1.31

Conventional method «00 ^ --'_ - · - _{2> n 2} .04 1.88

¹⁰⁰⁰ ™ · ο '5 3:92 0..3 2.07 2.02

1200 72.40 ί · ίν ^

Table 5

", Hi (I1IU)> - HH)

, _{l) 7} 0.45 3.42 13.27

Procedure geniiili der Ι'ΐΓπΗίιιημ «00 - · _{7 (l6} 14.20

1000 '^ ⁷ ' ^l _{1 | V;} 11.31

1200 ίο .: «'· ³¹ "-'

is

C ₁

I j

Forlsctzurm

proceedings

Reaction temp. i

Metal, liisen metal. nickel

I Cl

800 25.21 1000 58.72 1200 68.35

Conventional method

As can be seen from Table 5, the nickel content in the metallic end product of the process of the invention is above 10%, while the nickel content in the metallic products produced by the conventional process is low. When the starting material is treated, for example, at 1200 ⁰ C, so the invention is obtained a product with metaüisches 11.31% Nickel according to the method, while only a Nickelgehait can be obtained of 2.88% by the conventional method.

Accordingly, with the method according to the invention, an iron-rich nickel ore with only (Ii i

1.11

2.02

(Metal, liisenl
+ (Metal. Nickel!
(I + 11)

26.32
60.60

70.37

IV

(I'm old
metal. nickel
(Ii III) ν KK)

4.22
1.79
2.88

low nickel content to be worked up to a nickel-rich ferro-nickel intermediate product, with eil Method is used which was previously viewed as uneconomical.

As a standard for checking the fayalite image The X-ray diffraction diagram shown in FIG. 7 was recorded by Fayalit. In same: Way, this was shown in FIG. 8 reproduced X-ray diffraction diagram of the invention at 1000 ° C reduced sample added. The comparison of the two diffraction diagrams clearly shows that in the Fayalit method according to the invention was formed.

Example 3

Nickel magnesium silicate ore with the composition given in Table 2 was broken down to a grain size smaller than 0.25 mm and then calcined for 2 hours as described in Example 1 at 600 ° C. By adding 40 parts by weight of water to 1 part by weight of the ore calcined in this way a slurry was made. This slurry was fluidized for 1 hour by introducing the exhaust gas from the reduction process at a pressure of 10 kg / cm ² (gauge pressure). The thus fluidized slurry was filtered through a filter cloth with the slurry tank under a pressure of 10 kg / cm ² and the filtrate chamber under a pressure of 8.5 to 9 kg / cm ² .

The MgO yield was about 43%, while the NiO yield was 2.4%. The chemical « The composition of the silica-containing residue was determined. The results are in table ( summarized.

Table 6 Composition (%)
Loss on ignition SiO ₂ Fc ₂ O., AI ₂ O., CaO MgO Ni + Co material 5.64 49.45 18.95 0.74 0.30 19.19 3.57 Silica containing
Residue

140 parts by weight of iron-rich nickel ore (laterite) with the composition shown in Table 3 was used mixed with 100 parts by weight of silicon-containing residue of the composition given in Table 6 The composition of the mixture produced in this way is shown in Table 7.

Table 7

material

Composition (%)
Fe Ni

SiO,

MgO

CaO

AI ₂ O.,

Mixture of iron rich
Nickel ore and silicon oxide residue

35.66

2.19

21.22

8.25

Lanes 2.97

Glow plug

8.58

The MgO contained in the mixture (see Table 7) 6s. Accordingly, not everything according to Table 7 is in

As described above, forms S1O2 present during the mixture to form fayalite

Reduction of forsterite (2 MgO ■ SiO ₂ ). The grouting thus formed. The calculation shows that, based on da:

Forsterite forms solid solutions with fayalite. Total weight of the mixture, only 15.07% of the S1O2 to:

Ul

Formation of fayalite are available and that only ; about 27% of the iron, based on the total weight of the mixture, in this way through the S1O2 can be bound.

The mixture was reduced at 600, 800, 1000, 1200 or 1300 ^° C. for 1.5 hours. This reduction was carried out by adding 5% coke as a reducing agent in flowing argon in an experimental furnace.

For comparison, similar reductions were made using pure CO instead of using of coke, which acted as a solid reducing agent. Even with these comparative reductions the reduction chamber was 1.5 hours.

For further comparison purposes, the iron-rich nickel ore having the composition shown in Table 3 was used and the silica-containing residue having the composition shown in Table 6 separately, d. H. without being mixed together, reduced. The conditions of the reduction process were the same as for the mixture, with these separate reductions both with coke and with CO were carried out.

The results of these reductions are shown in Table 8 and the relationship between the reduction temperature and the degree of reduction in F i g. 9 shown.

Table 8

method

sample

Method according to the invention (1) Mixture of ore and residue

Reducing agent: coke (argon atmosphere)

Process according to the invention (2) Mixture of ore and residue

Reducing agent: pure CO

Known Process (1)

Known Process (2)

Silica-containing residue. Reducing agent: coke (Argon atmosphere)

iron-rich nickel ore (latent) reducing agent: pure CO

Reduction Metal. metal lemp. iron nickel (C) (%) (%) 600 0.16 0.07 600 0.18 0.04 1000 0.94 0.62 1200 12.29 2.41 1300 14.35 2.61 600 2.09 0.07 800 16.31 0.55 1000 23.31 1.40 1200 32.01 2.66 1300 16.95 2.64 600 0.25 0.27 800 0.06 0.24 1000 0.31 0.42 1200 1.85 1.11 1300 7.43 2.35 600 5.58 0.42 800 35.80 1.21 1000 72.53 1.72 1200 75.04 1.94 1300 73.21 2.02

The reduction process (1) according to the invention in Table 8 uses coke and argon to adjust one defined reducing atmosphere, while in process (2) according to the invention in Table 8 for this purpose pure CO is used. It should be noted that according to FIG. 5 in such a strongly reducing atmosphere actually no more fayalite should be formed. The equilibrium diagram shown in Fig. 5 however, gives the equilibrium between the pure components, which leads to the fact that these Equilibria in the actually occurring very much complicated systems are slightly shifted be able. For this reason, in the comparative example, it was possible to maintain a perfectly reproducible Reduction atmospheres also pure CO can be used without causing the fayalite formation and the essential conditions of equilibrium described above would have been disturbed.

If the reduction ^{temperature is above 1400 °} C., the fayalite can also be reduced by solid carbon, as in the blast furnaces for making pig iron. For this reason, at reduction ^{temperatures of 1400 °} C. or above, the amount of carbon added must be reduced to the absolute minimum that is necessary for reducing the iron and nickel.

From Table 8 and F i g. 9 also shows that the degree of reduction of iron and the amount of metallic iron in the reduction process according to the invention are reduced in comparison with the known process (2). The difference in the amounts of metallic iron increases at temperatures above 1000 ^° C., the temperature at which the formation of fayalite and solid solutions of fayalite and forsterite begins. This difference in the amount of metallic iron reflects the effectiveness of the presence of fayalite in suppressing iron reduction, that is, in masking the iron. In practice it has been shown that the control of the iron reduction by Fayalit is more reliable and more precise than a control by the mere setting of the reducing atmosphere.

With regard to the reduction to nickel, a comparison of the processes {\) and (2) according to the invention with the known processes (1) and (2) shows that the nickel reduction is not caused by the presence of

709 661/119

Fayalite is still adversely affected by the presence of solid solutions of fayalite and forsterite. About it In addition, according to the method according to the invention, the reduction to metallic nickel is also increased Temperature faster than the reduction according to the s known method (1). This acceleration and thus the increase in the degree of reduction of nickel is due to the fact that the reduced nickel Forms solid solutions with the metallic iron, thereby reducing the activity of the nickel and taking, ο Use of the iron contained in the ore breaks up the crystal structure of the nickel magnesium silicate ore, for example of the garnierite, is increased.

An examination of a non-molten metal sample μ prepared by the known method (1) showed that the reduced metal was in the form of very fine particles , the diameter of which was on the order of micrometers. It was found, however, that by adding an iron-rich nickel ore containing easily reducible iron oxides such as laterite, an increase in the grain size of the metallic particles could easily and effectively be achieved.

From Fig. 9 it can be seen that the degree of reduction of iron and nickel according to the method (2) according to the Invention decreased at 1300 ° C. This decrease in the degree of reduction is due to the fact that the Treated ores were already in the semi-molten state, causing the attack of the gas phase was made difficult.

From the sample prepared by the method (2) according to the invention at 1200 ° C, an X-ray was found movement diagram added. A comparison of this ir Fig. 10 X-ray diffraction diagram shown with the one shown in FIG. 7 clearly shows that fayalite and solid solvents in the sample examined of fayalite and forsterite templates.

The method according to the invention provides the following advantages:

a) Starting from the treatment products according to the invention, conventional Methods and devices Nickel-rich ferronickel or metallic nickel in high yield can also be made from iron-rich nickel ores with only a low nickel content.

b) Reducing atmospheres with a wide range of compositions can be solid, liquid or gaseous phase can be applied, whereby the practical implementation of the process is facilitated.

c) Since the silicon oxide-containing residue obtained after the separation of the magnesium oxide from the nickel-magnesium silicate ore usually contains nickel, the addition of this residue to the iron-rich nickel ore or to the iron-rich nickel oxide compared to pure SiO ₂ surcharges instead of the residue surcharges leads to an increase in the absolute amounts for the reduction of available nickel compounds.

For this purpose 10 sheets of drawings

Claims (9)

Patent claims: 1. A process for producing a reduced preliminary product for ferronickel deugging from nickel oxide-containing iron-rich starting material and nickel magnesium silicate ore, the nickel magnesium silicate ore being broken and calcined, characterized in that the calcination is ^{carried out at 500 to 800 0} C, that the calcined ore is suspended in water carbon dioxide-containing gas is pressed into the slurry with a COr partial pressure of at least 1 atm, that the slurry is separated by filtration into a magnesium-rich filtrate and a silicon dioxide-containing residue, that magnesium carbonate is precipitated by heating from the filtrate and then _{decomposed to MgO and CO 2} , that the solicium dioxide-containing residue is mixed with the iron-rich starting material and that the mixture is used in a CO / CO atmosphere of the composition 1% <CO / (CO + CO ₂ ) S 90% for the formation of fayalite and solid solutions of fayalite and forsteri t is heated to sufficient temperatures. 2. The method according to claim 1, characterized that the exhaust gas of the last heating stage as a carbon dioxide-containing gas to stir up the Slurry is used. 3. The method according to claim 1 or 2, characterized in that the starting material rich in iron Laterite and garnierite is used as nickel magnesium silicate ore. 4. The method according to any one of claims 1 or 2, characterized in that the nickel magnesium silicate ore is broken to a grain size finer than 0.25 mm. 5. The method according to any one of claims 1 or 2, characterized in that the slurry is made from 8 to 50 parts by weight of water and 1 part by weight of calcined ore 6. The method according to any one of claims 1 or 2, characterized in that the Auiiwirbelung and the filtration can be carried out with the carbon dioxide-containing gas under pressure and that the filtrate is exposed to atmospheric pressure to precipitate the magnesium carbonate 7. The method according to any one of claims 1 or 2, characterized in that the fillrate for precipitation of the magnesium carbonate is heated to the boilers. 8. The method according to any egg of claims 1 or 2, characterized in that the; Mixture as additional reducing agent coke is added. 9. The method according to any one of claims 1 or 2, characterized in that the mixture in one argon-containing atmosphere is heated