WO2015185457A1 - Method and plant for processing lateritic nickel ore - Google Patents

Abstract

Disclosed is a method for processing lateritic nickel ore, wherein the nickel ore is crushed and then separated into a fine fraction and a coarse fraction. According to the invention, the fine fraction is further processed separately from the coarse fraction or only the fine fraction is further processed in order to separate at least one nickel-containing material.

Description

 Process and plant for processing lateritic nickel ore

The invention relates to a method for processing lateritic nickel ore, wherein at least one nickel-containing substance is separated from the nickel ore. The invention further relates to a system for carrying out such a method.

Nickel is obtained either from sulfidic or lateritic nickel ores. The majority of the world's known nickel deposits are in the form of lateritic nickel ores.

In order to win nickel economically, the nickel content of the ore should be at least 0.5% by weight.

Sulphidic nickel ores were formed by magmatic processes. Lateritic nickel ores were formed by weathering of nickeliferous rocks. The chemical properties of the lateritic nickel ores, which are characteristic of each deposit, are influenced by the historical process of weathering and the composition of the rocks.

Typically, lateritic nickel ore deposits consist of a top layer, a limonite layer, a transition layer, and an underlying saprolitic layer. At least part of the nickel ore deposits also contain gait, ie fractions containing low levels of nickel or containing no nickel. At least part, possibly also the majority of the nickel is contained in the limonite ore fraction, which is comparatively rich in iron and nickel and low in magnesium and quartz. The nickel is usually bound in the form of iron oxide minerals, such as goethite, chromite and complex manganese oxides. Limonite ore fractions are usually rich in cobalt and have a relatively high level of free moisture, resulting in a doughy consistency with sometimes even thixotropic behavior. In saprolitic ore fractions, however, the separation of iron and nickel is more complete, the nickel in the form of silicates with a fairly high proportion of magnesia, such as serpentine, garnierite, nontronite, kaolinite or Magnesite, present. These minerals have less free moisture and are more abrasive than the minerals contained in the limonite ore fraction.

In lateritic nickel deposits, as a rule, both limonite and saprolitic ore fractions are to be found, but in strongly fluctuating conditions. In order to efficiently recover the contained nickel, limonite and saprolitic ore fractions should be processed differently due to the different minerals and their dissimilar properties.

It is known to separate nickel or the nickel-containing substances from lateritischen nickel ores hydrometallurgisch, pyrometallurgisch or by a combination of both methods. Examples of corresponding hydrometallurgical processes are "High Pressure Acid Leaching" (HPAL), "Pressure Acid Leaching" (PAL) and "Atmospheric Leaching" (AL), which may be sulfuric acid, hydrochloric acid, nitric acid or other acids The corresponding pyrometallurgical process is usually the so-called "Rotary Kiln / Electric Furnace" process, which involves preheating, calcining and usually also a pre-reduction in a rotary kiln and subsequent melting in an electric furnace to produce an iron-nickel crude product ( Ferronickel or nickel brick). The so-called "New Smelting Technology" (NST) combines flow-stream drying and calcination with a fluidized-bed reduction and an electric furnace to produce a ferro-nickel raw material (ferronickel) An example of a combined hydro- and pyrometallurgical process is the so-called " Caron "-V, in which the ore is selectively reduced after drying and comminution and leached in ammonia. Furthermore, in recent years, shaft furnace processes have been used to produce low nickel content products such as "Nickel Pig Iran" (NPI) and "Nickel Base Material" (NBM) as well as iron silicate slag. Based on this prior art, the present invention seeks to provide a way to win nickel as economically as possible from lateritic nickel ore.

This object is solved by the subject matter of patent claim 1. Advantageous embodiments of the method according to the invention and advantageous embodiments of the system according to the invention are subject matters of the further claims and will become apparent from the following description of the invention.

The invention is based on the idea that for the highest possible separation rate for the nickel with the lowest possible energy expenditure, the processes for separating nickel or nickel-containing substances from nickel ore should be optimally adapted to the nickel metal ore fractions to be processed, and in particular nickel ore fractions Although they contain nickel or nickel-containing substances, but for the chosen method is not well suited because it can be separated, no or only a small proportion of the nickel, as early as possible to exclude from processing. As a result, on the one hand, the energy expenditure for the processing can be kept low because the extracted portion is not further processed. On the other hand, this makes it possible to further process the reclaimed fraction in another process adapted to the properties of this fraction, in order to separate nickel or nickel-containing substances from this fraction with the greatest possible separation rate.

A further basic idea of the invention is that for all or at least most of the processes for separating nickel or nickel-containing substances from lateritic nickel ore a comminution process is provided relative to the beginning and that the effect of such comminution is on the one hand the limonitic portion, on the other hand the saprolitic portion of the Lateritic nickel ore, as well as the gait is different, which in particular on the different compositions and ingredients as well as the resulting different consistencies. In particular, such a comminution process may be "better" at the softer limonite portion rather than the more hard and abrasive saprolitic portion, which may result in correspondingly different particulate sizes of the comminuted portions, thus enabling the rather large saprolitic particles to be separated relatively easily Separate small limonitic particles of the crushed nickel ore in order to use them separately, as required, as well as gait and saprolitic particles.

Accordingly, the method according to the invention for processing lateritic nickel ore comprises at least comminuting the nickel ore and separating the comminuted nickel ore into a fine fraction and a coarse fraction, the fine fraction subsequently being processed separately from the coarse fraction and / or the coarse fraction separately from the fine fraction ( each) to separate at least one nickel-containing substance contained therein.

A plant for carrying out such a process comprises at least one comminuting device (eg ball mill or hammer mill) for comminuting the lateritic nickel ore, a separating device for separating the comminuted nickel ore into at least one fine fraction and a coarse fraction, and at least one further processing system for separating at least one nickel-containing substance from either the fines or the coarse fraction.

As said, it can be provided in the context of the method according to the invention, specifically the fines, which may substantially comprise the limonite portion of the nickel ore, and / or specifically the coarse fraction, which may substantially comprise the saprolitic portion of the nickel ore, to at least one thereof to separate nickel-containing substance. In this case, processes adapted to either the limonitic fraction or the saprolitic fraction are preferably used in order to be able to achieve the greatest possible separation rate. Likewise, it may be provided that the fine fraction, which may substantially comprise the saprolitic portion of the nickel ore, be specifically processed further and the coarse fraction, which may substantially comprise the gangue of the nickel ore, be discharged. This other part, not intended for further processing (with the aim of separating a nickel-containing substance), on the other hand, can be used in any other way or removed without being used. An essential advantage of the method according to the invention is then the reduced expenditure, in particular energy consumption, for the further processing of the corresponding portion as a result of the amount of the nickel ore to be further processed, which is reduced by the separated portion. In order to compensate for the expense of separating fines and coarse fraction through energy savings, the proportion to be rejected should be at least 2%, better still at least 5%, 8%, 10%, 12% or 15%.

Depending on, in particular, the nickel contents in the two fractions to be separated, it may also be advantageous to subject both fractions separately to a preferably optimally matched composition for the separation of the at least one nickel-containing substance in order to maximize the nickel contained in the nickel ore to win completely. For the system according to the invention, in addition to a first further processing system for separating at least one nickel-containing substance from the fine fraction, a second further processing system for separating at least one nickel-containing substance from the coarse fraction may be provided.

In a preferred embodiment of the method according to the invention can also be provided to return the coarse fraction in whole or in part in the crushing device, to which the plant may have a corresponding return line from the separator to the crushing device. This can serve, in particular, to further comminute comparatively large parts of the coarse fraction, either because they are too large for the further use intended for the coarse fraction, or because it is assumed on the basis that they still contain too much valuable material which is still present in the product Fines should be present. For subdivision of the coarse fraction into the portion to be recycled and the portion not to be returned, any subdivision device, for example a screening device, can be provided. The subdivision of the coarse fraction into a non-recoverable, fine coarse fraction and a coarse coarse fraction to be returned can also be effected in or by means of the separation apparatus itself, for which purpose these three outlets may have. The recycled fraction of the coarse fraction is preferably at most 15%, better at most 12%, 10%, 8%, 5% or 2%.

Advantageous for the comminution of the nickel ore and / or the separation into a fine fraction and a coarse fraction may be when the comminuted nickel ore is dried before the separation. This can be done both during or parallel to the comminution as well as in advance to it. The plant according to the invention can for this purpose comprise a dryer, in particular a riser dryer, for drying the nickel ore.

Particularly preferably, it can be provided that at least a part of the dryer is integrated into the comminution device (eg, configuration of the comminution device in a known form as a milling dryer). The integrated part of the dryer can also be a hot gas connection, through which hot gas is introduced into the comminuting device. The hot gas flows through and dries so the crushed or already crushed nickel ore. In this case, the flow through the nickel ore by means of the hot gas must not be limited to the crushing device, but can also be done in subsequent system parts, in particular a riser dryer. The hot gas can be generated for example by means of a separate burner of the system. As a hot gas but also a process or exhaust gas from a plant part, such as an air flow treatment device or a furnace (eg deck oven or rotary kiln), in particular calcination or melting furnace, the system according to the invention or a parallel operated system can be used. Advantageously, the absolute humidity (ratio of the mass of water to the total mass) in the crushed nickel ore is at most 25%, better at most 20%, 15%), 10% o, 4% o or at best at most 3%.

In order to achieve the greatest possible separation rate, it can be advantageously provided that the fine fraction which substantially comprises the limonitic portion of the nickel ore is preferably further processed by hydrometallurgy. If there is no further processing (with the aim of separating a nickel-containing substance) for the coarse fraction substantially containing the saprolitic portion of the nickel ore, this can be discharged from the process and, for example, landfilled.

With regard to the saprolitic portion of the nickel ore having coarse fraction can be provided that this is further processed pyrometallurgically in order to achieve the greatest possible separation rate in a known manner.

In the further processing of the coarse fraction with the aim of separating at least one nickel-containing substance, it can preferably be provided that it is at least partially comminuted further. For this purpose, the corresponding further processing system of the system according to the invention may comprise a further comminuting device.

The separation device of the system according to the invention can advantageously comprise a separator, a cyclone separator and / or a sieve device, the construction and modes of operation of which are well known and which have proven themselves for the separation of bulk materials fed into the mass flow.

The invention will be explained in more detail with reference to an embodiment shown in the drawings. In the drawing shows the

Fig. 1: a system according to the invention for the processing of lateritischem

Nickel ore in a schematic representation. The plant shown in FIG. 1 comprises a material feed e 1, via which lateritic nickel ore is fed to a comminuting device 2. The crushing device 2 is exemplified in the form of a hammer mill. In the area of the mouth of the material task 1 in the crushing device 2, a hot gas connection 3 is provided. Hot gas is introduced into the comminution device 2 via this. The hot gas flows through the nickel ore contained in the comminution device 2 before, during and after the comminution and dries this.

This throughflow also stops in a dryer 4 adjoining the comminution device 2 in the form of a riser-type dryer. The hot gas simultaneously acts as a carrier fluid through which the comminuted particles of nickel ore are conveyed into the riser dryer and within the riser dryer against gravity.

The dryer 4 is followed by a separator 5 in the form of a separator. In this, the crushed nickel ore is separated into a fine fraction and a coarse fraction.

The fines, which essentially comprise the limonite portion of the nickel ore, are conveyed from the separator 5 into a first further processing system 6 and are preferably incorporated therein by means of a hydrometallurgical process, e.g. a "high pressure acid leaching" process, a "pressure acid leaching" process or an "atmospheric leaching" process, processed to separate nickel-containing substances from the fines.

The coarse fraction, which essentially comprises the saprolitic portion of the nickel ore, and which may comprise, for example, between about 5% and 10% of the total nickel ore fed in, can be discharged from the process on the one hand and thus can not be used to obtain nickel-containing materials. For example, the discharged coarse fraction can then be transferred to a landfill 7. By discharging it is achieved that the coarse fraction is not carried out within the framework of the first processing system 6 hydrometallurgical process is processed, whereby the processing cost and in particular the corresponding energy requirements can be kept low. This can lead to a reduction of the energy consumption for the operation of the entire system by between 5% and 10%.

On the other hand, the coarse fraction can also be conveyed to a second further processing system 8, in which by means of a pyrometallurgical process, e.g. a "Rotary Kiln / Electric Furnace" process or the "New Smelting Technology", nickel-containing substances are separated from the coarse fraction. This has the advantage that the entire amount of the nickel ore supplied to the plant is used for the separation and consequently recovery of the nickel-containing substances, whereby by optimally adapting the processes to the fine and coarse fractions to be separately processed, in each case high individual degrees of separation and Consequently, a particularly high Gesamtseparierungsgrad for the production of nickel-containing substances from the nickel ore can be achieved. To prepare the coarse fraction for the separation of the nickel-containing substances, the second further processing system 8 may comprise a further comminution device 10, in which the particles of the coarse fraction are further comminuted.

In the system shown in FIG. 1, the possibility is provided to recycle the coarse fraction of the nickel ore partially or completely via a return line 9 to the material feed 1, in turn, through the comminution device 2, the dryer 4 and the To lead separator 5.

In a further embodiment, the fine fraction, which essentially comprises the saprolitic portion of the nickel ore and which is conveyed from the separation device 5 into a first further processing system 6, preferably by means of a pyrometallurgical process, for example a "Rotary Kiln / Electric Furnace" process or "New Smelting Technology", processed to separate nickel-containing substances from the fines. The coarse fraction, the gangue, ie shares that are low levels of nickel or contain no nickel, the nickel ore substantially covers and can make up, for example, between about 5% and 10% of the total supplied nickel ore, on the one hand from the process discharged and thus not be fed to the process for the extraction of nickel-containing substances.

For example, the discharged coarse fraction can then be transferred to a landfill 7. By discharging it is achieved that the coarse fraction is not processed in the context of the process carried out in the first further processing system 6, whereby the processing effort and in particular the corresponding energy requirement can be kept low. This can lead to a reduction of the energy consumption for the operation of the entire system by between 5% and 10%.

Reference numerals:

1. Material task

 2. Crushing device

3. Hot gas connection

 4th dryer

 5. Separator

 6. first processing system

7. Landfill

 8. second finishing system

9. return line

 10. further crushing device

Claims

Claims: 1. A method for processing lateritic nickel ore, wherein the nickel ore is comminuted and separated into a fine fraction and a coarse fraction, characterized in that the fine fraction is processed separately from the coarse fraction and / or the coarse fraction separately from the fine fraction to a nickel-containing material separate. 2. The method according to claim 1, characterized in that the crushed nickel ore is dried before separation. 3. The method according to any one of the preceding claims, characterized in that the fine fraction is processed hydrometallurgically. 4. The method according to claim 3, characterized in that the coarse fraction is discharged. 5. The method according to any one of the preceding claims, characterized in that at least part of the coarse fraction is comminuted again together with newly abandoned nickel ore. 6. The method according to any one of the preceding claims, characterized in that the coarse fraction is further processed pyrometallurgically. 7. The method according to any one of the preceding claims, characterized in that the coarse fraction is at least partially further crushed in the course of further processing. 8. Plant for carrying out a method according to one of the preceding claims with a crushing device (2) for comminuting the lateritic nickel ore and a separation device (5) for separating the comminuted nickel ore into a fine fraction and a coarse fraction, characterized by at least one further processing system (6, 8 ) to Separation of a nickel-containing substance from either the fines or the coarse fraction. 9. Plant according to claim 8, characterized by a first further processing system (6) for separating a nickel-containing substance from the fine fraction (69 and a second further processing system (8) for separating a nickel-containing substance from the coarse fraction. 10. Plant according to claim 8 or 9, characterized by a dryer (5) for drying the nickel ore. 11. Plant according to claim 10, characterized in that at least a part of the dryer (5) in the crushing device (2) is integrated. 12. Installation according to one of claims 8 to 11, characterized in that the further processing system (8) for separating the nickel-containing substance from the coarse fraction comprises a further crushing device (10). 13. Plant according to one of claims 8 to 12, characterized in that the separating device (5) comprises a separator, a cyclone separator and / or a screening device. 14. Plant according to one of claims 8 to 13, characterized by a return line (9) from the separating device (5) to the crushing device (2) for at least a part of the coarse fraction.