GB2596529A - A method for separating a non-hydraulic phase from a hydraulic phase in a recyclable industry product - Google Patents

Abstract

A method of separating an iron containing phase 110 from a sodium silicate and/or calcium silicate hydraulic phase 120 in steel making slag by exposing the slag to an environment which comprises water and carbon dioxide whereby the hydraulic phase 120 is hydrated. The slag is ground either before or during mixing with water. The hydration reaction is performed at a raised pressure (e.g. 10 bar or more) at room temperature, for example in an autoclave. The method produces particles 200 comprising a core 110 of the iron containing phase surrounded by an inner layer 125 of hydrated silica and an outer layer 140 of precipitated calcium carbonate. The layers 125 & 140 can be removed from the core 110 by grinding, with the core 110 then being separated for recycling into a steel making process. The method can be used to recycle the iron in BOF and LD slags which have high phosphorous content in the calcium silicate as the phosphorous 130 is accumulated in the layers 125 & 140.

Description

A method for separating a non-hydraulic phase from a hydraulic phase in a recyclable industry product The invention relates to a method of separating a non-hydraulic phase from a hydraulic phase in a recyclable industry product.

The invention can therefore relate to the technical field of treating recyclable industry products.

Industry products may contain valuable components which are recyclable, for example the iron of iron-rich waste products (e.g. from steelmaking processes). Due to high concentration of heavy metals in these products, they need to be discarded, which leads to excessive land-filling and high transportation costs. These conventional applications have become less interesting or is even forbidden by legislative (in some countries) nowadays due to either environmental issues or high transportation/land-filling costs, respectively. For example, in the case of steelmaking slag, in particular BOF slag, high concentrations of heavy metals have been considered as an environmental issue in Austria by legislative for conventional applications in building and road construction industries. Therefore, recycling of the material may provide an efficient usage of resources, while cost and law conflicts can be avoided.

Accordingly, there may be a demand for recycling the industry products (e.g. recycling the iron). For example, BOF slag, such as LD-slag, shows a significant concentration of valuable metals. Hence, LD-slag may be considered as a relatively low grade, but favorable, iron ore (e.g. 25% Fe) for steel industry.

However, recycling can be cumbersome and the quality of recycled products may be too low, when contaminants are present in said industry products. For example, a high phosphorous concentration in an BOF-slag (e.g. 1.06% P205) jeopardizes the quality of the final steel product by degradation of toughness properties and weldability.

Separating a contaminant from an industry product (for example dephosphorylation of iron-rich waste products such as BOF slags) remains a -2 -challenge. Liberation by crushing, grinding, classification and subsequent separation (magnetic separation, flotation, etc.) does not work with heavily intergrown hydraulic and non-hydraulic phases in an economic way.

With respect to the example of BOF-Slag material (as produced in steelmaking plants), regarding the separation of phosphorus from iron rich minerals, e.g. Das et.al. (2007): "an overview of utilization of slag and sludge from steel industries", Resources, Conservation & Recycling, 50, pages 40-57, describes lab tests for treating the LD-slag by magnetic separation and flotation but reported an unsuccessful separation process regarding separation of phosphorus and iron phases, when using fresh LD-slag.

It is an object of the invention to provide a method of separating a non-hydraulic phase and a hydraulic phase (which are intergrown) in a recyclable industry product in an efficient and environmentally friendly manner.

The object defined above may be solved by the subject matters described by the independent claims. The dependent claims describe preferred embodiments.

According to an exemplary embodiment of the invention, it is described a method of separating a non-hydraulic phase (e.g. an iron phase) from a hydraulic phase (e.g. a calcium-silicate phase) in a recyclable industry product, the method comprising: i) providing the recyclable industry product, wherein the hydraulic phase and the non-hydraulic phase (the phases co-exist) are intergrown, ii) performing a hydration reaction of the hydraulic phase using an hydroxy (OH) (group) and/or hydronium (H30+) (group) containing fluid (e.g. water or air) in order to obtain a rearranged hydrated phase (e.g. a silica gel), and thereby iii) providing an altered product, wherein the rearranged hydrated phase is dislocated with respect to the non-hydraulic phase (for example the hydrated phase is rearranged such that it is located (at least partially) around the non-hydraulic phase).

According to a further aspect of the invention, an altered product is described that is formed by the method described above. The altered product comprises: i) a non-hydraulic phase (e.g. an iron phase) core, H) a layer of a rearranged -3 -hydrated silica phase around the core, and iii) a layer of precipitated calcium-carbonate around the rearranged hydrated silica phase. In particular, a contaminant (e.g. phosphorus) is accumulated in the rearranged hydrated silica phase (or CaCO3).

In the context of this document, the term "phase" may refer to a region of material that is chemically uniform while physically distinct. In particular, a phase may be mechanically separable. For example, in a system consisting of ice and water in a glass jar, the ice cubes are one phase, the water is a second phase, and the humid air is a third phase over the ice and water. The glass of the jar is another separate phase. In another example, a product may contain at least one non-hydraulic phase (e.g. iron oxide) and a hydraulic phase (e.g. a calcium-silicate phase (e.g. orthosilicate) phase). If water and carbon dioxide are added, these also represent separate phases.

In the context of this document, the term "performing a hydration reaction" may refer to a method step, wherein the conditions are set such that a specific chemical hydration reaction takes place. For example, a hydraulic phase such as a calcium silicate may react with water (which contains OH-and H30+ ions) to a hydrated silica phase. In a preferred embodiment, this hydration reaction contains a spatial rearrangement of the hydrated phase with respect to the hydraulic phase.

According to an exemplary embodiment, the invention may be based on the idea that a method of separating a non-hydraulic phase and a hydraulic phase of a recyclable industry product can be provided in an efficient (low energy demand) and environmentally friendly manner, when the (grinded) recyclable industry product is subjected to a chemical hydration reaction with an OH (and/or hydronium) containing fluid (e.g. water).

The described process surprisingly changes the arrangement of the co-existing phases with respect to increasing the accessibility of the desired phases efficiently and without using thermal treatment techniques and/or (additional) hazardous chemical reagents. A soft acid leach (e.g. from water and carbon dioxide) may be used to improve the mineral processing behavior of the waste -4 -product, i.e. to enhance grindability, liberation behavior, and enable physical separation by floatation and magnetic separation in further steps.

In the case that at least one of the hydraulic phase and the non-hydraulic phase comprises a contaminant (e.g. phosphorus in the hydraulic phase) and/or a valuable component (e.g. iron in the non-hydraulic phase), the contaminant-containing phase can be easily and efficiently separated from the valuable-component comprising phase.

In summary, the described method may be performed in an easy control-able manner with a low energy and low cost process, without hazardous chemicals and thermal treatment (at high temperatures).

In a specific example, wherein carbon dioxide gas is applied to accelerate the hydration kinetics, said gas can be stored permanently in a solid state (e.g. calcium carbonate). Hereby, the carbon dioxide emission of a steel-making process may be reduced by 1.3% or more.

According to an embodiment, the hydrated phase is arranged essentially separated, in particular around, the non-hydrated phase. This may provide the advantage that the rearranged hydrated phase (former hydraulic phase) and the non-hydraulic phase can be efficiently separated (e.g. by mechanical treatment).

According to a further embodiment, the non-hydraulic phase comprises a metal (in particular iron). This may provide the advantage that the industry product can be considered as a valuable iron ore. According to an exemplary embodiment, the industry product comprises 20-30% iron (iron oxide) in the non-hydraulic phase and 1-2% phosphorus in the hydraulic phase.

According to a further embodiment, the hydraulic phase comprises a calcium-silicate (and/or a sodium-silicate), for example calcium ortho-silicate.

According to a further embodiment, the contaminant comprises at least one of the group that consists of phosphorus, vanadium, chromium, titanium (also aluminium, magnesium, sulfur, potassium, manganese). This may provide the -5 -advantage that a contaminant (contained in a specific phase) can be efficiently separated (for example phosphorus accumulated in silica phase lattice).

According to a further embodiment, the recyclable industry product is an iron-rich waste product from steelmaking. This may provide the advantage that an industrial product that emerges in enormous amounts can be efficiently and environmentally friendly recycled. According to an exemplary embodiment, the steel-production waste product comprises a blast oxygen furnace steelmaking (BOP) slag, more in particular a Linz-Donawitz (LD, slag).

According to a further embodiment, the grinded waste product comprises an average grain size (in particular an absolute grain size) of 100 pm or smaller. This may provide the advantage that the chemical reactions can be performed very efficiently.

The grinding can take place before and/or during the hydration reaction. In an example, the waste material is grinded down to a (essentially 98-100 0/0) grain size < 100 pm. The grain size may be defined by the grain diameter (average or largest diameter per grain). Further, the grain size may be smaller than 100 pm, defined by the wire mesh of screen.

According to a further embodiment, the pressure is elevated, in particular higher than 5 bar, in particular higher than 10 bar, more in particular 15 bar or more. In a preferred embodiment, the pressure is 16 bar or more. This may provide the advantage that the hydration reaction can be performed especially efficient without increasing the temperature.

According to a further embodiment, performing the hydration reaction further comprises: i) providing water as the hydroxy (OH, OH-) and/or hydronium (H30+) containing fluid and carbon dioxide, ii) forming the rearranged hydrated phase from the hydraulic phase and the water; and Hi) forming carbonic acid using the carbon dioxide (and partially the hydrated phase). PH is for example in the range 4 to 7. -6 -

According to a further embodiment, performing the hydration reaction further comprises: i) forming the rearranged hydrated phase (in particular silica hydrate) from the hydraulic phase, and thereby ii) arranging the rearranged hydrated phase (at least partially) around the non-hydraulic phase; and iii) forming calcium carbonate (CaCO3) from the carbonic acid and precipitating the calcium carbonate (at least partially) around the rearranged hydrated phase.

An exemplary example of the described hydration reaction is described in the following, wherein the non-hydraulic phase is an iron-phase and wherein the hydraulic phase is a calcium-silicate phase: Exposing the industry product to water may lead to hydration of the calcium-silicate phase, for example according to one of the following reactions: 2 Ca35105 + 7 H20 -> (CaO)3 (5i02)2 (H20)4 + 3 Ca(OH)2 2 Ca2SiO4 + 4 H20 -> (CaO)3 (Si02)2 (H20)3 + Ca(OH)2.

The produced silica gel can be tobermorite or a silica gel beyond tobermorite from (CaO/3i02) ratio point of view. Furthermore, Ca(OH)2 (calcium hydroxide) is produced in this example.

Introduction of CO2 gas into water can generate carbonic acid, according to the following reaction: CO2 + H20 -> H2CO3 The generated carbonic acid can sequestrate to carbonate or bi-carbonate ion: H2CO3 -> HCO3-+ H+ H2CO3 -> C032 + H2 The produced calcium hydroxide may bind with the generated (bi)-carbonate ion, and, as a result, the concentration of calcium-hydroxide decreases, and the -7 -balance of the hydration reaction moves to the right side. Thus, even more calcium-silicate may be decomposed or hydrated and mobilized.

Calcium carbonate may precipitate according to the following reactions: Ca(OH)2 + C032-+ 2H+ -> CaCO3 (precipitated) + 2 H20 Ca(OH)2 + HCO3-+ H+ -> CaCO3 (precipitated) + 2 H20 The hydration and the precipitation reactions may be summarized as follows: 2 Ca35i05 + 4 H20 + 3 CO2 -> (CaO)3 (5i02)2 (H20)4 + 3 CaCO3 (precipitated) 2 Ca25iO4 + 3 H20 + CO2 -> (Ca0)3(Si02)2(H20)3 + CaCO3 (precipitated).

The produced calcium carbonate may form, after precipitation, a rim surrounding the iron phase (core) particles. In addition, decomposition of the calcium-silicate phase may result in formation of rearranged hydrated calcium-silicate (silica phase), which is mobilized from the interior of a grain. The silica phase may then be precipitated between the iron phase core and the calcium carbonate layer.

According to a further embodiment, the reaction comprises agitating in a reaction device, in particular in an autoclave reactor. This may provide the advantage that the chemical reaction can be performed especially efficient. Every suitable reaction vessel such as a reactor (in particular an autoclave reactor) may be used to perform the chemical reaction. An agitation (mixing, moving, distributing) during the reaction may be advantageous. An autoclave reactor may comprise a pressure chamber to carry out industrial and scientific processes requiring elevated temperature and pressure in relation to ambient temperature. The combination of a reaction vessel and mechanical stress (mechanical acceleration) may be possible. Grinding media (in particular spheres) may be added to the vessel with stirrer (attrition mill) or to a vessel without stirrer (ball mill, vibrating mill) to enhance the reaction and continuously scrub the surface. -8 -

According to a further embodiment, performing the reaction does not comprise an (essential) elevation of the reaction temperature, in particular ambient temperature and/or room temperature. This may provide the advantage that energy can be saved, and the chemical reaction can be performed in an environmentally friendly manner. For example, if the reaction is performed in an autoclave reactor, no temperature elevation is needed. The ambient temperature (or room temperature) may be sufficient.

According to a further embodiment performing the reaction does (essentially) not comprise the application of additional chemical reactants, in particular strong acids. This may provide the advantage that costs can be saved, and the chemical reaction can be performed in an environmentally friendly manner. In a preferred embodiment, the addition of water and carbon dioxide (under pressure) is sufficient to perform the decomposition reactions. Hence, no further chemicals (such as aggressive and environmentally harmful acids) are necessary.

According to a further embodiment, the method further comprises removing (in particular by mechanical treatment in order to break up precipitated layers) the rearranged hydrated phase from the altered product in order to obtain a refined product. This may provide the advantage that the non-hydraulic phase and the hydraulic phase (now rearranged and hydrated) can be efficiently separated.

The basic processing operations may include: crushing by breaking and grinding, separating according to the grain size by sieving and classifying, separating according to different physical chemical properties of the grains (density, magnetizability, surface wettability, electrical conductivity, solubility, differences in the response to electromagnetic radiation) and solid/liquid separation or any combination of these operations to products with constant quality.

According to a specific example, the aim is to separate a gel-shaped silicate phase and calcium carbonate precipitation product from a non-hydrated phase on the basis of physical and/or chemical differences relevant to separation.

According to an example, the size separation is obtained by wet classification (e.g. hydro cyclones or screw classifiers) or sedimentation processes in gravity or -9 -centrifugal field (e.g. selective flocculation, centrifuges, thickeners, etc.) as the hydrated products and non-hydrated products differ in size (due to selective breakage behavior).

Further, the material may be physically sorted either magnetically, e.g. by using a matrix separator at a high gradient magnetic field. E.g. a wet high gradient magnetic separation (HGMS) may be applied. Alternatively or additionally, a separation by flotation may be performed. All wet separating processes may be prepared or substituted by classification (size separation using sedimentation processes in the gravitational or centrifugal field).

According to a further embodiment, the method further comprises: mechanically treating (in particular by using friction force and/or grinding) the altered waste product in order to break up precipitated layers. This may provide the advantage that the altered waste product can be refined in an efficient and environmentally friendly manner.

Figure 1 illustrates a method of separating a non-hydraulic phase from a hydraulic phase in a recyclable industry product in order to obtain an altered product according to an exemplary embodiment of the invention.

Figure 2 shows microscopic images of the recyclable industry product and the altered product according to an exemplary embodiment of the invention.

Before referring to the drawing, exemplary embodiments will be described in further detail, some basic considerations will be summarized based on which exemplary embodiments of the invention have been developed.

According to an exemplary embodiment of the invention, the following characteristics can be provided: i) having two groups of phases or minerals with hydraulic and non-hydraulic properties, ii) wherein the hydraulic phases may carry one or more target element or a component (contaminant), which shall be separated from the non-hydraulic phases or minerals which is rich in one or more element or component, iii) wherein the valuable target elements or components can be situated in either hydraulic or non-hydraulic phases.

-10 -According to an exemplary embodiment of the invention, the method comprises mobilizing a hydraulic Ca-Si phase with valuable or contaminating elements in the lattice structure by a hydration process in a liquid phase to improve the growth ratios in a grain/particle with the aim of enabling an economical phase separation process of non-hydraulic phases by means of treatment technology.

According to an exemplary embodiment of the invention, BOF slag cannot be recycled into the steel-making process mainly due to the high phosphorous content in the calcium-silicate ("C25")-phase. Energy saving physical separation processes, especially magnetic separation of untreated BOF slag (on ground material down to 100% -25 pm), did not result in a successful separation of phosphorous carrying phases. However, pretreatment of the slag by grinding down (to 100°/0 smaller than 100 pm) followed by CO2 assisted autoclave hydration process surprisingly prepared a successful physical separation process (in particular in the grain size class 1000/0 < 25 pm) by rearrangement of the phase intergrowth pattern to increment the accessibility of the desired phase at ambient temperature.

According to an exemplary embodiment of the invention, an accelerated hydration process for BOF-Slag material to alter the phase intergrowth pattern at ambient temperature is described. Soft acid leach is used to improve the mineral processing behavior of the material, i.e. to enhance grindability, liberation behavior and improve physical separation by flotation and magnetic separation prepared or substituted by classification (cyclones, centrifuges,....).

According to an exemplary embodiment of the invention, the following advantages can be provided: i) feasibility for recycling of BOF (LD) slag to the steel-making process and reduction of iron loss in the waste material, ii) quantitative decrease of the inevitable produced waste material by the steelmaking industrial sites, Hi) low energy demand process, prevention of thermal treatment methods and prevention of usage of hazardous chemical components, iv) from ecological concern, the process uses the emitted CO2 gas and stores part of the gas in a solid status, which a worldwide concern, and v) easy controlling and simplicity of the process principle.

According to an exemplary embodiment of the invention, the following points are addressed: i) soft acid leach in non-toxic acids for BOF-slag, ii) pretreatment of the slag to improve physical separation of phosphorous, iii) selective improvement of grindability, change of intergrowth pattern, iv) cheap physical separation, v) separation of pre-treated slag material, vi) acceleration of hydration process using carbonation reaction, and vii) physical dephosphorization of BOF slag.

According to an exemplary embodiment, an enhanced hydration process is applied in presence of carbon dioxide as a catalyzer to act on the phosphorus carrying mineral (calcium silicate), which is persistent due to the permanent consumption of carbon dioxide. Pressure (16 bars) and mechanical agitation has been applied (e.g. in an autoclave) in order to accelerate the hydration reaction and improve the conversion in the desired mode. The reaction products (silica rich phase and calcium carbonate), still carry the phosphorous. The altered phase arrangement provides improved physical separability properties, e.g. by magnetic separation, than the untreated material, concerning higher liberation of iron-rich minerals from phosphorus hosting phases. The recovery of iron oxides at equal separation settings with material treatment process improved by 75% in the magnetic product, while only 25% of phosphorus was recovered to the magnetic fraction. For example, separation of the treated material by an autoclave process after an attrition process (to 25 pm or finer) followed by wet high gradient magnetic separation (HGMS) in open circuit was tested successfully.

According to an exemplary embodiment, a pre-conditioning stage was foreseen to alter the intergrowth pattern of the co-existing phases, with respect to the hydraulic properties of the calcium-silicate phases. To accelerate the hydration reaction, CO2 gas was introduced to the slag suspension as a catalyzer reagent. As a result of the chemical reactions, the phosphorus bearing phase (calcium-silicate) was mobilized from the interior of the particles and precipitated at the expose surface of the grains, in the form of calcium carbonate and silica phases. The new arrangement of the phases serves the higher accessibility of the phosphorus bearing components. Thereafter, the process-chain was followed by -12 -a mechanical treatment, applying dominantly friction force, to liberate the newly formed rims from the iron containing components. Accordingly, magnetic separation as a selective method was applied to discard the phosphorus hosting phases.

Figure 1 shows a grain (component) of an industry product 100. In a specific embodiment, the industry product is a waste product from steel production, in particular, the iron-rich waste product 100 is a Linz-Donawitz (LD) slag which is a specific blast oxygen furnace steelmaking (B0F) slag. The industry product 100 has been grinded in order to increase the surface and accessibility (for example grains with a diameter of 100 pm or smaller). The industry product 100 comprises a non-hydraulic phase 110 (e.g. an iron phase such as iron ore, iron oxide) that forms a matrix, wherein a hydraulic phase (e.g. a calcium-silicate phase) 120 is embedded in said matrix (intergrown phases). The hydraulic phase 120 comprises for example calcium-orthosilicate (Ca2SiO4) and carries a contaminant (e.g. phosphorus) 130. The industry product 100 is placed into an autoclave reactor, wherein it is exposed to (liquid) water and (gaseous) carbon dioxide (CO2) under high pressure, in particular 16 bar or more. Further, the content of the autoclave reactor is agitated. In this manner, the hydraulic phase 120 is hydrated by the water (during a hydration reaction) and forms a rearranged hydrated phase (e.g. (Ca0)3(Si0)2(H20)3 or (CaO)3 (Si02)2 (H20)4. The carbon dioxide and a part of the hydrated phase then react to carbonic acid. This decomposition leads to a rearrangement of phases. After these altering reactions, a rearranged hydrated phase (e.g. a silica(-rich)-phase) 125 is formed around the non-hydraulic phase 110 that forms a core. Additionally, calcium carbonate (CaCO3) is formed from the carbonic acid and precipitates around the rearranged hydrated phase 125. Hereby, the contaminant 130, which has originally been carried by the hydraulic phase 120, is now accumulated in the rearranged hydraulic phase 125. Thereby, an altered product 200 has been provided, wherein the rearranged hydrated phase 125 with the contaminant 130 is essentially separated (i.e. dislocated) from the non-hydraulic phase 110. The obtained altered product 200 hence comprises: i) a non-hydraulic phase (e.g. iron phase) core 110, ii) a layer of the rearranged hydrated (silica) phase 125 around the non-hydraulic phase core 110, and iii) a layer of the precipitated calcium-carbonate 140 around the rearranged hydrated -13 -phase 125, wherein the contaminant 130 is accumulated in the rearranged hydrated phase 125. This altered product 200 can be further refined by discarding the precipitated rearranged hydrated phase 125 in order to obtain a refined product (in an exemplary example, a BOF slag comprising 700/0 or more of iron and 0.75% (in particular 0.50/0) or less of phosphorus).

During the process, the pH may decrease down to 6 under ambient pressure, and may decrease further, when a higher pressure is applied. This is because the reduction of the pH may be a function of pressure during treatment of the material. The re-suspended material (in distilled water) after completion of the process and dewatering would reach a pH between 8.5 to 10 depending on the process conditions.

Figure 2 shows at the left side a SEM image of the recyclable industry product 100, wherein the non-hydraulic phase 110 and the hydraulic phase 120 are co-existing and intergrown with each other. At the right side, Figure 2 shows a further SEM image of the altered product 200 with a non-hydraulic core 110 (e.g. an iron phase core), a layer of a rearranged hydrated (silica) phase 125 around the non-hydraulic core 110, and a layer of precipitated calcium-carbonate 140 around the rearranged hydrated (silica) phase 125.

Claims (15)

1. -14 -Claims 1. A method of separating a non-hydraulic phase (110) from a hydraulic phase (120) in a recyclable industry product (100), the method comprising: providing the recyclable industry product (100), wherein the hydraulic phase (120) and the non-hydraulic phase (110) are intergrown; performing a hydration reaction of the hydraulic phase (120) using a hydroxy-group and hydronium-group containing fluid in order to obtain a rearranged hydrated phase (125); and thereby providing an altered product (200), wherein the rearranged hydrated phase (125) is dislocated with respect to the non-hydraulic phase (110).
2. 2. The method according to claim 1, wherein the rearranged hydrated phase (125) is arranged essentially separated, in particular around, the non-hydrated phase (110).
3. 3. The method according to claim 1 or 2, wherein the non-hydraulic phase (110) comprises a metal, in particular iron.
4. 4. The method according to any one of the preceding claims, wherein the hydraulic phase (120) comprises a calcium-silicate.
5. 5. The method according to any one of the preceding claims, wherein the hydraulic phase (120) comprises a contaminant (130), in particular at least one of the group that consists of phosphorus, vanadium, chromium, titanium.
6. 6. The method according to any one of the preceding claims, wherein the recyclable industry product (100) is an iron-rich waste product from steelmaking.
7. 7. The method according to any one of the preceding claims, further comprising: -15 -grinding the recyclable waste product (100), in particular to an average grain size of 100 pm or smaller.
8. 8. The method according to any one of the preceding claims, wherein performing the hydration reaction comprises: elevating the pressure, in particular to 10 bar or more, more in particular to 16 bar or more.
9. 9. The method according to any one of the preceding claims, wherein performing the hydration reaction further comprises: providing water as the hydroxy-group and hydronium-group containing fluid and carbon dioxide; forming the rearranged hydrated phase (125) from the hydraulic phase (120) and the water; and forming carbonic acid using the carbon dioxide.
10. 10. The method according to claim 9, wherein performing the hydration reaction further comprises: forming the rearranged hydrated phase (125), in particular silica hydrate, from the hydraulic phase (120), and thereby arranging the rearranged hydrated phase (125) at least partially around the non-hydraulic phase (110); and forming calcium carbonate, CaCO3, (140) from the carbonic acid and precipitating the calcium carbonate (140) at least partially around the rearranged hydrated phase (125).
11. 11. The method according to any one of the preceding claims, wherein performing the hydration reaction does not comprise an essential elevation of the reaction temperature, in particular ambient and/or room temperature.
12. 12. The method according to any one of the preceding claims, wherein performing the hydration reaction does essentially not comprise the application of additional chemical reactants, in particular strong acids.
13. -16 - 13. The method according to any one of the preceding claims, further comprising: removing, in particular by mechanical treatment in order to break up precipitated layers (140), the rearranged hydrated phase (125) from the altered product (200) in order to obtain a refined product.
14. 14. An altered product (200) formed according to any one of the claims 1 to 13, comprising: an iron phase core (110); a layer of a rearranged hydrated silica phase (125) around the iron phase core (110); and a layer of precipitated calcium-carbonate (140) around the rearranged hydrated silica phase (125).
15. 15. The altered product (200) according to claim 14, wherein a contaminant (130), in particular phosphorus, is accumulated in the rearranged hydrated silica phase (125).