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US 2019/0345066 A1Published application
Method for Manufacturing Briquettes Containing a Calcium-Magnesium Compound and an Iron-Based Compound, and Briquettes Obtained Thereby
AssigneeS. A. Lhoist Recherche et Developpement
InventorsGuillaume Criniere, Michael Nispel
Life of this patent
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Abstract
Composition in the form of green or thermally treated briquettes comprising at least one “quick” calcium-magnesium compound comprising an iron-based compound and method of production thereof as well uses thereof.
Claims32
1:
- Method for manufacturing a calcium-magnesium composition in the form of briquettes, comprising the following steps:
- i. supplying a pulverulent mixture comprising at least one “quick” calcium-magnesium compound, said mixture comprising at least 40 wt % of CaO+MgO equivalent relative to the weight of said composition and having a Ca/Mg molar ratio greater than or equal to 1, preferably greater than or equal to 2, more particularly greater than or equal to 3;
- ii. feeding a roller press with said homogeneous mixture,
- iii. compressing said pulverulent mixture in said roller press, with obtaining a calcium-magnesium composition in the form of green briquettes, and
- iv. collecting said green briquettes,
- characterized in that said pulverulent mixture comprises an iron-based compound present at a content of at least 3%, preferably at least 12%, preferably at least 20%, preferably at least 30%, more preferably at least 35 wt % of Fe2O3 equivalent relative to the weight of said composition, said iron-based compound having a very fine granulometric distribution characterized by a median size d50 below 100 μm, preferably below 50 μm as well as a size d90 below 200 μm, preferably below 150 μm, preferably below 130 μm, more preferably below 100 μm, wherein said at least one “quick” calcium-magnesium compound comprising at least 40 wt % of CaO+MgO equivalent comprises a fraction of particles of calcium-magnesium compound having a particle size ≤90 μm having at least 20 weight % CaO equivalent with respect to the weight of said pulverulent mixture, and wherein said iron-based compound comprises at least 50 weight %, preferably at least 60 weight %, more preferably at least 70 weight %, more preferably at least 80 weight % and particularly more than 95 weight % of iron oxide under the form of hematite Fe2O3 with respect to the total weight of the iron-based compound and in that the rollers of the roller press developing linear speeds at the periphery of the rollers between 10 and 100 cm/s, preferably between 20 and 80 cm/s, and linear pressures between 60 and 160 kN/cm, preferably between 80 and 140 kN/cm, and even more preferably between 80 and 120 kN/cm.
3 more elements
2:
- Method according to claim 1, in which said compression step is effected in the presence of a binder or a lubricant, more particularly selected from the group consisting of binders of mineral origin such as cements, clays, silicates, binders of vegetable or animal origin, such as celluloses, starches, gums, alginates, pectin, glues, binders of synthetic origin, such as polymers, waxes, liquid lubricants such as mineral oils or silicones, solid lubricants such as talc, graphite, paraffins, stearates, in particular calcium stearate, magnesium stearate and mixtures thereof preferably calcium stearate and/or magnesium stearate, at a content between 0.1 and 1 wt %, preferably between 0.15 and 0.6 wt %, more preferably between 0.2 and 0.5 wt % relative to the total weight of said briquettes.
3:
- Method according to claim 1, further comprising a thermal treatment at a temperature lower or equal to 1150° C., preferably lower or equal to 1100° C., preferably higher or equal to 900° C., preferably according to the rule (predetermined duration)/(thermal treatment temperature−1000° C.)>5.
4:
- Method according to claim 3, wherein said thermal treatment of green briquettes occur for a predetermined duration of between 3 and 20 minutes, preferably greater than or equal to 5 minutes and less than or equal to 15 minutes.
5:
- Method according to claim 1, in which said “quick” calcium-magnesium compound is quicklime.
6:
- Method according to claim 1, further comprising, before said supplying of a homogeneous pulverulent mixture,
- v. feeding a mixer with at least 40 wt % of CaO+MgO equivalent of a “quick” calcium-magnesium compound relative to the weight of said composition and with at least 3 wt %, preferably at least 12 wt %, more preferably at least 20 wt %, preferably at least 25 wt %, more preferably at least 30 wt %, more preferably at least 35 wt % of Fe2O3 equivalent of an iron-based compound relative to the weight of said composition, said iron-based compound having a very fine granulometric distribution characterized by a median size d50 below 100 μm, preferably below 50 μm as well as a size d90 below 200 μm, preferably below 150 μm, preferably below 130 μm, more preferably below 100 μm;
- said at least one “quick” calcium-magnesium compound comprising at least 40 wt % of CaO+MgO equivalent comprises a fraction of particles of calcium-magnesium compound having a particle size ≤90 μm having at least 20 weight % CaO equivalent with respect to the weight of said pulverulent mixture, and wherein said iron-based compound comprises at least 50 weight %, preferably at least 60 weight %, more preferably at least 70 weight %, more preferably at least 80 weight % and particularly more than 95 weight % of iron oxide under the form of hematite Fe2O3 with respect to the total weight of the iron-based compound
- vi. mixing said “quick” calcium-magnesium compound with said iron-based compound for a predetermined length of time, sufficient to obtain an approximately homogeneous pulverulent mixture of said “quick” calcium-magnesium compound and of said iron-based compound.
1 more element
7:
- Method according to claim 6, in which said binder or lubricant is added to the mixer, and in which said binder or lubricant is included in said homogeneous pulverulent mixture.
8:
- Method according to claim 1, in which said “quick” calcium-magnesium compound contains at least 10 wt % of quicklime in the form of ground particles.
9:
- Method according to claim 1, further comprising a pre-treatment step of the briquettes under modified atmosphere containing at least 2 vol % CO2 and at most 30 vol % CO2, preferably at most 20 vol % CO2, more preferably at most 15 vol % CO2, even more preferably at most 10 vol % CO2 with respect to the modified atmosphere.
10:
- Method according to claim 1, wherein said pulverulent mixture further comprises at least 10% of particles of “quick” calcium-magnesium compound having a particle size ≥90 μm and ≤5 mm with respect to the weight of the pulverulent mixture.
11:
- Method according to claim 1, wherein said pulverulent mixture further comprises between 10% and 60% of particles of “quick” calcium-magnesium compound having a particle size ≥90 μm and ≤5 mm with respect to the weight of the pulverulent mixture.
12:
- Method according to claim 1, wherein said iron-based compound is present at an amount of at least 20 wt %, preferably at least 25 wt %, more preferably of at least 30 wt %, in particular of at least 35 wt % relative to the total weight of the pulverulent mixture.
13:
- Method according to claim 1, wherein the weight percentage of CaO equivalent in the fraction of “quick” calcium-magnesium compound having a particle size <90 μm relative to the total of the weight percentage of quicklime in the fraction of calcium-magnesium compound having a particle size <90 μm and the % of Fe2O3 equivalent of said iron-based compound having a very fine granulometric distribution is <40, preferably <38, more preferably <36% and higher than 20%, preferably higher than 22%, preferably 24%.
14-26. (canceled)
27:
- Composition in the form of green briquettes comprising at least one “quick” calcium-magnesium compound and an iron-based compound, characterized in that the composition comprises at least 40 wt % of CaO+MgO equivalent relative to the weight of said composition, said composition having a Ca/Mg molar ratio greater than or equal to 1, preferably greater than or equal to 2, more preferably greater than or equal to 3 and characterized in that said iron-based compound is present at a content of at least 3 wt %, preferably at least 12 wt %, more preferably at least 20 wt %, preferably at least 30 wt %, more preferably at least 35 wt % of Fe2O3 equivalent relative to the weight of said composition, said iron-based compound having a very fine granulometric distribution characterized by a median size d50 below 100 μm, preferably below 50 μm as well as a size d90 below 200 μm, preferably below 150 μm, preferably below 130 μm, more preferably below 100 μm, wherein said at least one “quick” calcium-magnesium compound comprising at least 40 wt % of CaO+MgO equivalent comprises a fraction of particles of calcium-magnesium compound having a particle size ≤90 μm having at least 20 weight % CaO equivalent with respect to the weight of said composition;
- said iron-based compound comprises at least 50 weight %, preferably at least 60 weight %, more preferably at least 70 weight %, more preferably at least 80 weight % and particularly more than 95 weight % of iron oxide under the form of hematite Fe2O3 with respect to the total weight of the iron-based compound.
28:
- Composition in the form of green briquettes according to claim 27, in which said calcium-magnesium compound is quicklime.
29:
- Composition in the form of green briquettes according to claim 27, in which said “quick” calcium-magnesium compound comprises:
- fine particles of calcium-magnesium compound selected from fine particles rejected in screening in the production of the pebbles of said “quick” calcium-magnesium compound, calcium-magnesium filter dust at a concentration from 0 wt % to 90 wt % relative to the total weight of said “quick” calcium-magnesium compound, and
- from 10 to 100 wt % of quicklime in the form of ground particles, relative to the total weight of said “quick” calcium-magnesium compound.
30:
- Composition in the form of green briquettes according to any one of claim 27, having a BET specific surface area greater than or equal to 1 m2/g, preferably greater than or equal to 1.2 m2/g, more preferably greater than or equal to 1.4 m2/g.
31:
- Composition in the form of green briquettes according to claim 27, having a porosity greater than or equal to 20%, preferably greater than or equal to 22%, more preferably greater than or equal to 24%.
32:
- Composition in the form of green briquettes according to claim 27, further comprising a binder or a lubricant, more particularly selected from the group consisting of binders of mineral origin such as cements, clays, silicates, binders of vegetable or animal origin, such as celluloses, starches, gums, alginates, pectin, glues, binders of synthetic origin, such as polymers, waxes, liquid lubricants such as mineral oils or silicones, solid lubricants such as talc, graphite, paraffins, stearates, in particular calcium stearate, magnesium stearate, and mixtures thereof, preferably calcium stearate and/or magnesium stearate, at a content between 0.1 and 1 wt %, preferably between 0.15 and 0.6 wt %, more preferably between 0.2 and 0.5 wt % relative to the total weight of said briquettes.
33:
- Composition in the form of green briquettes according to claim 27, further comprising at least 10% of particles of “quick” calcium-magnesium compound having a particle size ≥90 μm and ≤5 mm relative to the total weight of the composition.
34:
- Composition in the form of green briquettes according to claim 27, further comprising between 10% and 60% of particles of “quick” calcium-magnesium compound having a particle size ≥90 μm and ≤5 mm relative to the total weight of the composition.
35:
- Composition in the form of green briquettes according to claim 27, wherein the weight percentage of CaO equivalent in the fraction of “quick” calcium-magnesium compound having a particle size <90 μm relative to the total of the weight percentage of quicklime in the fraction of calcium-magnesium compound having a particle size <90 μm and the % of Fe2O3 equivalent of said iron-based compound having a very fine granulometric distribution is <40, preferably <38, more preferably <36% and higher than 20%, preferably higher than 22%, preferably 24%.
36-44. (canceled)
45:
- Composition in the form of thermally treated briquettes, comprising at least one iron-based compound, said composition comprising at least 40 wt % of CaO+MgO equivalent relative to the weight of said composition and having a Ca/Mg molar ratio greater than or equal to 1, preferably greater than or equal to 2, more preferably greater than or equal to 3, characterized in that said iron-based compound is present at a content of at least 3 wt %, preferably at least 12 wt %, more preferably at least 20 wt %, preferably at least 30 wt %, more preferably at least 35 wt % of Fe2O3 equivalent relative to the weight of said composition, said iron-based compound comprising at least 60% of calcium ferrite, expressed by weight of Fe2O3 equivalent, relative to the total weight of said iron-based compound expressed by weight of Fe2O3 equivalent, at least 40 wt %, preferably 50 wt % of said calcium ferrites are under the form of monocalcium ferrite CaFe2O4.
46:
- Composition in the form of thermally treated briquettes according to claim 45, in which said iron-based compound comprises at least 70%, preferably at least 80%, and even more preferably at least 90 wt % of calcium ferrite relative to the total weight of said iron-based compound.
47:
- Composition in the form of thermally treated briquettes according to claim 45, having a BET specific surface area greater than or equal to 0.4 m2/g, preferably greater than or equal to 0.6 m2/g, more preferably greater than or equal to 0.8 m2/g.
48:
- Composition in the form of thermally treated briquettes according to claim 45, having a porosity greater than or equal to 20%, preferably greater than or equal to 22%, more preferably greater than or equal to 24%.
49:
- Composition in the form of thermally treated briquettes according to claim 45, in which the thermally treated briquettes have a Shatter test index below 8%, preferably below 6%, preferably below 4%, and more preferably below 3%, in particular below 2%, said Shatter test index being the percentage by weight of fines under 10 mm generated after 4 drops from 2 m starting from 10 kg of product, the fines being quantified by sieving through a screen with square mesh of 10 mm after 4 drops from 2 m.
50:
- Composition in the form of thermally treated briquettes according to claim 45, characterized in that it further comprises particles of “quick” calcium-magnesium compound, preferably particles of quicklime having a two-dimensional size above 63 μm and under 5 mm, observable by scanning electron microscopy coupled to energy dispersive analysis, in a section of said briquette and covering at most 20% of the area of said section and preferably at most 10% of the area of said section.
51:
- Composition in the form of thermally treated briquettes according to claim 45, characterized in that it further comprises particles of “quick” calcium-magnesium compound, preferably particles of quicklime having a two-dimensional size above 63 μm and under 5 mm, observable by scanning electron microscopy coupled to energy dispersive analysis, in a section of said briquette and covering at least 20% of the area of said section and preferably at most 60% of the area of said section.
52-63. (canceled)