SE422334B - Process for binding an agglomerate - Google Patents

Abstract

The invention relates to a process for the preparation of an agglomerate, especially by rolling a particulate material into spheres, characterized in that a fibrous material is incorporated in the agglomerate before, during or after shaping it. The particulate material is preferably an inorganic substance, especially an ore, and more especially an iron ore of the oxide type, while the fibrous material is composed of mineral fibres, especially rock wool, such as diabase wool, and/or of glass fibres.

Description

7904325-5 2 limits, for example down to 0.1 mm, down to 0.05 mm, down to 0.01 mm or 0.001 mm. These upper resp. lower limits can refer to 10% of the material but also an interval e.g. 90, 75 or 50% of the material weight. However, even finer or coarser materials may be included in the agglomerates, provided that they are agglomerable.

Agglomeration methods of various kinds can be used, preferably rolling of particulate material into balls or pellets in devices in the form of drums, cones or plates.

Agglomeration by rolling into spheres is usually carried out with the addition of liquid, preferably water or aqueous solutions of organic or inorganic substances. It is also possible to incorporate in the agglomeration other adhesives commonly used in agglomeration, such as organic adhesives of various kinds, preferably polymers, such as cellulose, starch, curable synthetic resins, etc., as well as inorganic additives, such as bentonite or other clays. , lime, cement.

The amounts of these binders can be kept within the normally used intervals or reduced, e.g. up to a maximum of 50 or% of the quantities normally used.

According to the invention, fibers refer to elongate bodies, the extent of which in the longitudinal direction amounts to at least 5, preferably at least 10 times the extent in any direction perpendicular thereto. The cross-sectional shape of the fibers perpendicular to the longitudinal direction may vary depending on the method of production but is preferably close to circular or with a relatively largest dimension: minimum dimension in the cross-section, which amounts to a maximum of 5: 1, preferably a maximum of 3: 1 and in particular a maximum of 2: 1.

The average diameter of the fibers perpendicular to the longitudinal direction can vary within wide limits depending on the method of production.

Preferably at least 90% of the fibers have a thickness of less than 1 mm, in particular less than 0.5 mm and in particular less than 0.1 mm, especially less than 0.05 mm. A common upper limit for this value is 0.025 mm or even 0.015 mm, in some cases 0.005 mm.

Usual values of the average value of the fiber diameter for mineral fibers are 1 - 10 μm and in particular about 2 - 851m, especially about Slym.

The fiber length can be varied depending on the agglomerated material. Usual upper limit values for 100% and preferably 90% of the amount of fiber are up to 20 mm or up to 10 mm but also shorter fibers, such as up to 5 mm or 3 mm, can be used. The fiber length is adjusted together with the fiber diameter for the forming method in question. A lower limit for the fiber length is usually 1 mm and preferably 5 mm.

The fibers can be produced e.g. by fiber formation of melt by drawing through spinnerets, by fiber formation of a melt jet with rotating drum, rotating plate, rotating wheel, by blowing a jet of melt into fibers or by combining these methods, such as atomizing a jet of melt on a wheel or a plate combined with blowing with nozzles.

The composition of the fibers for mineral fibers can be varied within wide limits and suitable ranges are given in the following table: SiO2 Al2O3 Ca0 Mg0 8203 Na2O - KZO 50-65 3-15 5-15 2-5 l-12 l-18 -35 10-20 40- 45 2-8 - - -45 7-15 10-35 6-15 - - 50-55 6-15 25-35 2-6 - 2-3 34-44 10-20 25-41 l-18 - - 45 -50 12-15 9-12 7-10 - 2-4 and -12% Fe2O3 Further examples are given in the following table. The levels of SiO2, Al2O3, MgO and Ca0 can vary by 5% above or below the stated values and other constituents are optional.

% ABCDEFGHI Si02 46 55 44 62 37 35 47 45 40 AIZO3 14 8 7 4 14 ll 14 3 10 CaO 18 30 17 7 35 39 16 43 41 Mgo ss 3 11 1o 2 - FeO 6 2,5 9 0,5 l 8 1 - Mno 1 - 0,5 - 1,0 0,5 1 g - - Na 0 2 l 13 2 l - 2 2,5 ~ KZO 'l 3 2 4 2,5 ll - B203 - - - 5 - - - - - Bao - - - 2 - - - - - Residue 4 - 13,5 0,5 - - - 4 9 Particularly preferred are rock wool type fibers made from basic rock, e.g. of greenstone, basalt, diabase, optionally with the addition of lime or dolomite, preferably in an amount of up to 30, e.g. 10 - 20% by weight. These may have the following chemical composition as a percentage by weight: SiO2 45, Al2 O3 14, Ca0 20, MgO 7, FeO 6. The levels of these constituents may vary by 35%, preferably by 310% of the stated content values. Other constituents may be other oxides, such as MnO, Na 2 O 3, K 2 O, TiO 2, etc.

The amount of fibers in the agglomerates is preferably at most 20% by volume, in particular at most 10% by volume and especially at most% by volume, but also lower levels, such as at most 2% by volume or at most 1% by volume, can be used. The lower content limit preferably amounts to at least 0.01 volume percent, in particular at least 0.05 and especially 0.1 volume percent, but also higher contents, such as 0.5 or 1 volume percent, can be chosen as lower content limits. Suitable content limit ranges are, for example, 0.1 - 5 and especially 0.25 - 2.5% by volume.

These values are based on the solids volume of the agglomerated particles and the fibers. The agglomerated particles preferably have a relatively spherical shape, for example a difference between the largest and smallest dimension of on average no more than 5: 1 of the individual particles.

The fibers can be incorporated homogeneously throughout the volume of the agglomerates or distributed with different fiber densities within different parts of the agglomerates, e.g. on average by more than 50% or 75% of the fiber volume within an outer layer occupying less than 50% or less than 25% of the particle volume.

The direction of the fibers within the agglomerates can be random or layered. More than 50 and preferably more than 75% by volume of the fibers may be directed radially or within 300 from a radial direction in the agglomerates or be directed tangentially or within 300 or 600 from a tangential direction in the agglomerates, if their shape is approximated by spherical shape.

The agglomerates may also contain at least 25, e.g. at least 50 and also at least 75% by volume of the fibers distributed within more than one, preferably two or three concentric layers. Preferably, the fibers within these layers are arranged randomly or predominantly tangentially, for example with more than 50 or more than 75% of the fibers directed within 60 and preferably within 300 from the tangential direction. These layers preferably occupy at least 10%, e.g. at least 25% or at least 50% of the total agglomerate volume, and each of the layers suitably occupies at least 5%, e.g. at least 10% or at least% of the agglomerate volume. The thickness extent of the layers in relation to the radial extent of the agglomerates can also be at least 5%, e.g. at least 10% or even at least 25 or 50% of the radial extent of the agglomerates from an imaginary center point. This information may refer to layers with a fiber content that is present alternately with fiber-free layers, or layers with increased fiber content in relation to adjacent layers.

The size of the agglomerates, in particular agglomerates produced by rolling balls, amounts, for example, to a maximum of 50 mm, preferably not more than 40 mm, in particular not more than 30 and especially not more than 15 mm in diameter. The lower diameter of the agglomerate may also be, for example, at most 2 mm, preferably at most 5 mm and in particular at most 8 or at most 10 mm. Suitable intervals are, in particular for iron ore balls, for example 5 - 20 mm or - 30 mm.

The fibers can be added in whole or in part to the starting material which is agglomerated, for example subjected to rolling, for example added to a water slurry of particles before dewatering, for example fine iron ore particles before dewatering, after grinding or enrichment or possibly during enrichment. Fibers added to a liquid suspension of particles can facilitate the removal of liquid, e.g. dewatering of a water slurry of ore concentrate. The fibers can also be added in whole or in part before or during the agglomeration, in particular the rolling into balls. It is also possible, during rolling, to produce balls with a high fiber content alternating with layers with a low or no fiber content, in particular if the agglomeration or ball rolling is carried out in several steps with the intention of balls whose size exceeds a certain minimum value in one or more steps. followed by continued ball filling, wherein the fibers can be added in one or more of the ball rolling steps, preferably the last ball rolling step or steps, or between the ball rolling steps.

Fibers can suitably be added in a later part of a ball rolling step, e.g. near the outlet from the step, so that the fibers are incorporated in the outer part of the agglomerate layer applied in the step, e.g. in a cylinder, cone or plate for ball rolling. The agglomeration device can also be operated so that the larger agglomerates in the batch are enriched in a part of the batch, preferably at the surface of the batch, the fibers being preferably supplied to the larger or almost finished agglomerates (balls). It is also possible to add a lower volume content of fibers in a first ball rolling step and a higher volume content of fibers in a subsequent ball rolling step.

It is particularly suitable to carry out a final ball rolling step or fiber application step, wherein fibers are incorporated in a surface layer of the ball to bond the ball together.

It is also possible to supply fibers of different composition and / or dimensions, such as thickness and length, uniformly homogeneous within the agglomerates (by agglomerates is meant here as in other respects in connection with the present invention also balls or pellets prepared by rolling) or uniformly distributed within the same layer of the agglomerates, or fibers of different composition and / or dimensions can be used within different parts of the agglomerates. The fibers may comprise fibers with a low melting point or softening point, preferably below 100 ° C and especially below 800 ° C, e.g. 500 - 700 ° C, as well as fibers with a high melting point or softening point, preferably above 100 ° C and in particular above 1200 ° C, these being able to be distributed within the same parts of the agglomerates or distributed within different parts of the agglomerates. According to one embodiment, fibers with a low softening point, which enable good bonding to the particles at low temperature, are distributed within an outer part of the agglomerates, possibly together with fibers with a high softening temperature, in order to ensure good bonding at low temperature, in particular low -temperature reduction of the outer part of iron ore balls or sintering at low temperature.

The fibers can be supplied to the agglomerates by fiber production in the immediate vicinity of the addition site, e.g. the agglomeration device and transport of the produced fibers directly to this place, for example by air or gas transport.

It is also possible to modify the surface of the fibers by adding, for example, particulate material to the surface of the fibers immediately after the fiber formation, when the fibers are still in a moldable state, so that the supplied particulate material is hot bonded to the fibers.

The applied particulate material can be used to increase the friction between the fibers and the agglomerated particulate material or consist of materials which, when heated or affected by moisture, act as a binder between the fibers and the agglomerated material. Examples of particulate matter that can be added to the fibers are silica, water glass, lime.

For agglomeration of ore, in particular iron ore, a fiber composition is preferably used, which means that slag-forming constituents can be omitted in whole or in part from the agglomerates or from the charge in which the agglomerates are incorporated. For example, in this way so-called single beads with a desired ratio (Ca, Mg0): SiO2 (basicity). The basicity can be low (acid bullets), e.g. 0 - 0.5 or 0.8 or 1.0, medium high, e.g. 0.5 - 1.5 or 0.8 - 1.2, and high, e.g. 1.0 - 2.0 or higher, e.g. 1,2 - 1,6 or 1,2 - 1,4. Even higher values, e.g. 1.5 - 4 or 1.8 - 3.5, e.g. 2 - 3, can be used. The Ca0: CaO + Mg0 ratio can vary e.g. from 1 to 0.2 or 0.9 - 0.4, e.g. 0.8 - 0.5.

Claims (10)

7904325-3 PATENT REQUIREMENTS 1. A process for the production of agglomerates, preferably by rolling balls, of ores or ore concentrates consisting of ores of iron, nickel, cobalt, copper, zinc, lead or tungsten, characterized in that the agglomerates incorporate from 0.05 to a maximum of 2% by volume of one or more mineral fiber materials produced by forming a melt into fibers, which consist of slag gold fibers, glass fibers and / or rock gold fibers, e.g. diabase wool fibers. Process according to Claim 1, characterized in that the amount of fibers is up to 1% by volume, preferably at least 0.1% by volume and in particular at least 0.5% by volume. 3. A method according to claim 1 or 2, characterized in that the fibers are incorporated into the agglomerated material when it is present as an aqueous dispersion and / or before and / or during the formation of the material into agglomerates. A method according to any one of the preceding claims, characterized in that the fibers are incorporated homogeneously in the agglomerates or with elevated content within one or more concentric layers in the agglomerates, preferably within a surface layer of at most 50% by volume. Method according to one of the preceding claims, characterized in that at least 90% of the fibers have a thickness of less than 0.05 mm, preferably less than 0.025 mm, in particular less than 0.015 mm and preferably an average value of the diameter between 1 and 10 / Jm, in particular between 2 and 8; 1m, and a length of up to 50 mm, preferably up to 20 mm, in particular up to 10 mm or up to 5 mm or up to 3 mm. 7-904325- “3 m Process according to any one of the preceding claims, characterized in that iron ore or iron ore concentrate is agglomerated, in particular oxidically containing one or more of the oxides FeO, Fe 3 O 4 and Fe 2 O 3 and hydrated oxides, the amount and composition of the fibers being preferably so selected that the agglomerates have a composition which is suitable for a melting process, in particular so-called single agglomerates or agglomerates with a basicity (CaO + MgO / SiO2) below 1, between 1 and 2 or above 2, and preferably with a CaO: CaO + MgO ratio of 0.2 to 1. A method according to any one of the preceding claims, characterized in that the fibers are incorporated into agglomerates prepared by ball rolling, in particular using a ball rolling drum or ball rolling disc, the size of the agglomerates preferably not exceeding 40 mm, e.g. not more than 15 mm, possibly with a minimum size of 2 mm, in particular with agglomerates with a size of 10-30 mm. Process according to one of the preceding claims, characterized in that the fibers are incorporated in agglomerates which also contain at least one other organic or inorganic binder, such as bentonite or other clays, lime, cement, preferably in an amount of not more than 50%. or not more than 20% of the normal amount of such binder required. 9. A method according to any one of the preceding claims, characterized in that the particle size of the agglomerated ore material is up to 1 mm and in particular up to 0.1 mm or up to 0.05 mm. 10. A method according to any one of the preceding claims, characterized in that fibers with a softening temperature below 1000 ° C are incorporated, e.g. falls below 800 ° C, or exceeds 100 ° C, e.g. exceeds 1200 ° C, or incorporates a mixture of such fibers. 7904325-3 SUMMARY. The invention relates to a process for the production of agglomerates, in particular rolling of spheres, of particulate material, which is characterized in that a fibrous material is incorporated in the agglomerates before, during or after the molding. The particulate material is preferably an inorganic material, in particular ore, preferably oxidic iron ore, and the fibers are mineral fibers, in particular rock wool, such as diabase wool, and / or glass fibers.