Method for Manufacturing Briquettes Containing a Calcium-Magnesium Compound and an Iron-Based Compound, and Briquettes Thus Obtained

Patent metadata

Field	Value
Publication number	US-2019292626-A1
Application number	US-201716307567-A
Country	US
Kind code	A1
Filing date	Jul 7, 2017
Priority date	Jul 8, 2016
Publication date	Sep 26, 2019
Grant date	—

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.

First claim

1 : Method for manufacturing a calcium-magnesium composition in the form of briquettes, comprising the following steps:
i. supplying a homogeneous 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 pulverulent mixture, iii. compressing said pulverulent mixture in said roller press, obtaining a calcium-magnesium composition in the form of green briquettes, iv. collecting said green briquettes; and said method is characterized in that said homogeneous pulverulent mixture further comprises an iron-based compound present at a content of at least 12%, preferably at least 20%, preferably at least 30%, more preferably at least 35 wt % of Fe 2 O 3 equivalent relative to the weight of said composition, said iron-based compound having a very fine granulometric distribution characterized by a median size d 50 below 100 μm, preferably below 50 μm as well as a size d 90 below 200 μm, preferably below 150 μm, preferably below 130 μm, more preferably below 100 μm and in that the rollers of the roller press develop 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.

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 of said green briquettes at a temperature between 900° C. and 1200° C., preferably between 1050° C. and 1200° C., preferably between 11000° C. and 1200° C.

4 : Method according to claim 1 , comprising a step of thermal treatment of said green briquettes 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 12 wt %, more preferably at least 20 wt %, preferably at least 30 wt %, more preferably at least 35 wt % of Fe 2 O 3 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 d 50 below 100 μm, preferably below 50 μm as well as a size d 90 below 200 μm, preferably below 150 μm, preferably below 130 μm, more preferably below 100 μm; 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.

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 % CO 2 and at most 30 vol % CO 2 , preferably at most 25 vol % CO 2 , preferably at most 20 vol % CO 2 , more preferably at most 15 vol % CO 2 , even more preferably at most 10 vol % CO 2 with respect to the modified atmosphere.

10 : 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 12 wt %, more preferably at least 20 wt %, preferably at least 30 wt %, more preferably at least 35 wt % of Fe 2 O 3 equivalent relative to the weight of said composition, said iron-based compound having a very fine granulometric distribution characterized by a median size d 50 below 100 μm, preferably below 50 μm as well as a size d 90 below 200 μm, preferably below 150 μm, preferably below 130 μm, more preferably below 100 μm.

11 : Composition in the form of green briquettes according to claim 10 , in which said calcium-magnesium compound is quicklime.

12 : Composition in the form of green briquettes according to claim 10 , 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.

13 : Composition in the form of green briquettes according to anyone claim 10 , having a BET specific surface area greater than or equal to 1 m 2 /g, preferably greater than or equal to 1.2 m 2 /g, more preferably greater than or equal to 1.4 m 2 /g.

14 : Composition in the form of green briquettes according to claim 10 , having a porosity greater than or equal to 20%, preferably greater than or equal to 22%, more preferably greater than or equal to 24%.

15 : Composition in the form of green briquettes according to claim 10 , having a high reactivity with water defined by a value of t 60 below 10 min, preferably below 8 min, preferably below 6 min, and more preferably below 4 min.

16 : Composition in the form of green briquettes according to claim 10 , 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, paraffns, stearates, in particular calcium stearate, magnesium stearate, and mixtures thereof, preferably calcium stearate an

Assignees

• Lhoist Rech Et Developpement Sa

Inventors

• Criniere Guillaume
• Nispel Michael

Classifications

• C04B2111/0087

  for metallurgical applications · CPC title

• C04B2111/00732

  for soil stabilisation · CPC title

• C04B2111/00758

  for agri-, sylvi- or piscicultural or cattle-breeding applications · CPC title

• C04B2111/00887

  Ferrous metallurgy · CPC title

• C04B14/308

  Iron oxide · CPC title