Patent US2982530A successfully refreshed from Google Patents.
EP0399786A2
Expired / Lapsed
EP
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Refractory linings capable of resisting sodium and sodium salts
Assignee: Rio Tinto Alcan International Ltd
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Filing: 1990-05-22
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Granted: —
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Expires: 2010-05-22
Abstract
Abstract Refractory linings (28) for use in containers (20) which contact sodium or sodium salts at high temperatures and containers (20) provided with such linings, e.g. reduction cells and furnaces. The linings comprise three layers (29, 30 and 31) at least after an initial period of use. The first layer (29) is made of aluminosilicate material having an alumina:silica ratio of at least 0.85 and a porosity of about 25% or less. The second layer (30) is made of an aluminosilicate material having an alumina:silica ratio of at least 0.85 and a porosity in the range of about 25-50%. The third layer (31) is of highly insulating refractory material adjacent to an outer wall (22) of the container having a porosity of more than about 50%. The aluminosilicate used for one or more of the layers may be self-densifiable or non-self-densifiable calcined red mud. The linings resist degradation by the sodium or sodium salts while providing good thermal insulation.
Inventors
- 👤 Claude Allaire
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-28 14:48
CPC Classifications
F; F27; F27D; F27D1/00; F27D1/0003; F27D1/0006; B; B32; B32B; B32B18/00; C; C04; C04B; C04B35/00; C04B35/66; C25; C25C; C25C3/00; C25C3/06; C25C3/08; C25C3/085; C25C7/00; C25C7/005; C04B2111/00; C04B2111/00474; C04B2111/00612; C04B2235/00; C04B2235/02; C04B2235/30; C04B2235/32; C04B2235/3201; C04B2235/34; C04B2235/3427; C04B2235/3463; C04B2235/3472; Y; Y02; Y02P; Y02P10/00; Y02P10/25
Claims Analysis
Total Claims: 29
Claim 1
Independent Claim
138 words
A container having an internal volume (19) for containing sodium or sodium salts at high temperature, an outer wall (22) and a refractory lining (28) separating said internal volume from said outer wall, characterized in that said refractory lining (28) comprises a first layer (29) of an aluminosilicate refractory material having an alumina:silica ratio of at least 0.85 by weight and a porosity of about 25% or less, a second layer (30) of an aluminosilicate refractory material having an alumina:silica ratio of at least 0.85 by weight and a porosity of about 25-50%, said second layer (30) lying beneath said first layer (29) closer to said outer wall, and a third layer (31) of insulating refractory material beneath said second layer (30) closer to said outer wall, said insulating material having a porosity of more than about 50%.
Claim 2
Dependent Claim
138 words
A container having an internal volume (19) for containing sodium or sodium salts at high temperature, an outer wall (22) and a refractory lining (28) separating said internal volume from said outer wall, characterized in that said refractory lining (28) comprises a first layer (29) of an aluminosilicate refractory material having an alumina:silica ratio of at least 0.85 by weight and a porosity of about 25% or less, a second layer (30) of an aluminosilicate refractory material having an alumina:silica ratio of at least 0.85 by weight and a porosity of about 25-50%, said second layer (30) lying beneath said first layer (29) closer to said outer wall, and a third layer (31) of insulating refractory material beneath said second layer (30) closer to said outer wall, said insulating material having a porosity of more than about 50%.
Claim 3
Dependent Claim
33 words
A container according to Claim 1 characterized in that said aluminosilicate refractory material of said first and/or said second layer (29 and/or 30) has an alumina:silica ratio of at least 1.2 by weight.
Claim 4
Dependent Claim
29 words
A container according to Claim 1 or Claim 2 characterized in that said material of said first layer (29) has a water content of less than 5% by weight.
Claim 5
Dependent Claim
32 words
A container according to Claim 1, Claim 2 or Claim 3 characterized in that said material of said second layer (30) has a water content of less than about 5% by weight.
Claim 6
Dependent Claim
59 words
A container according to any preceding claim characterized in that said first and second layers (29 and 30) have suitable thicknesses and thermal insulation values to ensure that said insulation material of said third layer (31) is subject to a temperature of less than about 700°C during use and is protected from sodium or sodium salts in said container.
Claim 7
Dependent Claim
36 words
A container according to any preceding claim characterized in that said material forming said first layer (29) is an aluminosilicate material selected from products A, B, C and D identified in Table 1 of the disclosure.
Claim 8
Dependent Claim
26 words
A container according to Claim 6 characterized in that product D is dried or calcined to reduce the water content to less than 5 wt. %.
Claim 9
Dependent Claim
36 words
A container according to any preceding claim characterized in that said material forming said second layer (30) is an aluminosilicate material selected from products VCXSO, VCXS, VC2XB and VC2XO identified in Table 2 of the disclosure.
Claim 10
Dependent Claim
31 words
A container according to any preceding claim characterized in that said insulating refractory material of said third layer (31) is a compressible material selected from calcium silicate-based materials and mica-based materials.
Claim 11
Dependent Claim
128 words
A container according to Claim 9 characterized in that said insulating refractory material of said third layer (31) is one selected by carrying out the following steps: (a) selecting a range of product thermal conductivities having a 20% variation of the values in each range; (b) identifying different insulating products whose room temperature thermal conductivities fall within one of said selected ranges; (c) measuring the percentage loss of room temperature thermal conductivity of all said identified products after compression at 40% of their initial thickness, (d) rejecting all products having a change of thermal conductivity at 40% compression that is higher than a minimum value of said products by at least 20%, leaving remaining products and (e) using one of said remaining products as said insulating refractory material.
Claim 12
Dependent Claim
50 words
A container according to any preceding claim characterized in that said aluminosilicate material of said first and/or said second layer (29 and/or 30) is an aggregate produced by calcining red mud for a time sufficient to remove water therefrom and to produce a product resistant to sodium and/or sodium compounds.
Claim 13
Dependent Claim
23 words
A container according to Claim 11 characterized in that said aluminosilicate material of said first layer (29) is a self-densifiable red mud refractory.
Claim 14
Dependent Claim
44 words
A container according to Claim 12 characterized in that said aluminosilicate material of said second layer (30) is a self-densifiable, but non-self-densified, red mud refractory and said aluminosilicate material of said first layer (29) is the same red mud refractory which has undergone self-densification.
Claim 15
Dependent Claim
44 words
A container according to any preceding claim which is an aluminum production cell having an electrically conductive lining (24) for use as a cathode, characterized in that said refractory lining (28) is located between said electrically conductive lining (24) and said outer wall (22).
Claim 16
Dependent Claim
159 words
A container having an internal volume for containing sodium or sodium salts at high temperature, said container having an outer wall (22) and a refractory lining (28) separating said internal volume from said outer wall, characterized in that said refractory lining (28) comprises a first layer (29 and 30) of self-densifiable calcined red mud refractory having an alumina:silica ratio of at least 0.85 by weight and a porosity in the range of 25-50%, and a second layer (31) beneath said first layer (29 and 30) closer to said outer wall (22) of insulating refractory material having a porosity of more than 50%, said first layer (29 and 30) being sufficiently thick that, in use, an 830°C isotherm passes through said layer above a surface thereof which contacts said second layer (31) and in that said calcined red mud is capable of self-densifying to a porosity less than 25% when contacted with sodium or sodium salts at temperatures above 830°C.
Claim 17
Dependent Claim
159 words
A container having an internal volume for containing sodium or sodium salts at high temperature, said container having an outer wall (22) and a refractory lining (28) separating said internal volume from said outer wall, characterized in that said refractory lining (28) comprises a first layer (29 and 30) of self-densifiable calcined red mud refractory having an alumina:silica ratio of at least 0.85 by weight and a porosity in the range of 25-50%, and a second layer (31) beneath said first layer (29 and 30) closer to said outer wall (22) of insulating refractory material having a porosity of more than 50%, said first layer (29 and 30) being sufficiently thick that, in use, an 830°C isotherm passes through said layer above a surface thereof which contacts said second layer (31) and in that said calcined red mud is capable of self-densifying to a porosity less than 25% when contacted with sodium or sodium salts at temperatures above 830°C.
Claim 18
Dependent Claim
56 words
A process for producing a particulate refractory aluminosilicate material having an alumina:silica ratio of at least 0.85 by weight, characterized in that said process comprises drying red mud derived from the Bayer process of extracting alumina from bauxite, calcining said red mud at a temperature up to 1350°C and crushing the calcined product to form particles.
Claim 19
Dependent Claim
56 words
A process for producing a particulate refractory aluminosilicate material having an alumina:silica ratio of at least 0.85 by weight, characterized in that said process comprises drying red mud derived from the Bayer process of extracting alumina from bauxite, calcining said red mud at a temperature up to 1350°C and crushing the calcined product to form particles.
Claim 20
Dependent Claim
41 words
A process according to Claim 16 characterized in that said red mud has an alumina:silica ratio of less than about 1.2, which process additionally comprises removing sufficient silica-containing sand from said red mud to raise said ratio to 1.2 or higher.
Claim 21
Dependent Claim
116 words
A process according to Claim 16 for producing a calcined product which self-densifies in the presence of sodium and/or salts at temperatures above about 830°C, characterized in that said process comprises calcining a red mud having a value of R of less than 1 but greater than 0.05, wherein: wherein: Na₂O = the molar fraction of Na₂O in the product originating from the decomposition of the soluble salts in the red mud during calcination; SiO₂ = the molar fraction of free SiO₂ in the red mud product; S = the ratio of the specific surface area (SSA) of the calcined red mud particles to the maximum SSA value which is obtained from the -65 mesh material.
Claim 22
Dependent Claim
113 words
A process according to Claim 16 for producing a calcined product which does not self-densify in the presence of sodium salts at temperatures above about 830°C, characterized in that said process comprises calcining a red mud having a value of R of 1 or more, wherein wherein: Na₂O = the molar fraction of Na₂O in the product originating from the decomposition of the soluble salts in the red mud during calcination; SiO₂ = the molar fraction of free SiO₂ in the red mud product; S = the ratio of the specific surface area (SSA) of the calcined red mud particles to the maximum SSA value which is obtained from the -65 mesh material.
Claim 23
Dependent Claim
120 words
A process according to Claim 16 for producing a calcined product which does not self-densify in the presence of sodium salts at temperatures above 830°C, characterized in that said process comprises calcining red mud at a temperature below 950°C, to impart to said red mud a value of R less than 0.05 wherein: wherein: Na₂O = the molar fraction of Na₂O in the product originating from the decomposition of the soluble salts in the red mud during calcination; SiO₂ = the molar fraction of free SiO₂ in the red mud product; S = the ratio of the specific surface area (SSA) of the calcined red mud particles to the maximum SSA value which is obtained from the -65 mesh material.
Claim 24
Dependent Claim
83 words
A process according to Claim 18 or 19 characterized in that said red mud initially has a different value for R, and said value for R is adjusted prior to calcination of said red mud by at least one method selected from the group consisting of (a) reducing the value of Na₂O by washing said red mud, (b) adding material which contribute to the Na₂O value, (c) removing silica-bearing sand from the red mud, and (d) adding silica-bearing materials to said red mud.
Claim 25
Dependent Claim
28 words
A refractory aluminosilicate material having an alumina:silica ratio of at least 0.85 by weight characterized in that said material is produced by a process according to claim 16.
Claim 26
Dependent Claim
44 words
A refractory aluminosilicate aggregate having an alumina:silica ratio of at least 0.85 by weight and the ability to self-densify in the presence of sodium compounds at temperatures above about 830°C, characterized in that said aggregate is produced by a process according to Claim 18.
Claim 27
Dependent Claim
47 words
A refractory aluminosilicate aggregate having an alumina:silica ratio of at least 0.85 by weight and an inability to self-densify in the presence of sodium compounds at temperatures above about 830°C, characterized in that said aggregate is produced by a process according to Claim 19 or Claim 20.
Claim 28
Dependent Claim
135 words
A process for selecting an insulating refractory material for use in a lining for a container for containing sodium or sodium salts at high temperature, characterized in that said process comprises the steps of: (a) selecting a range of product thermal conductivities having a 20% variation of the values in each range; (b) identifying different insulating products whose room temperature thermal conductivities fall within one of said selected ranges; (c) measuring the percentage loss of room temperature thermal conductivity of all said identified products after compression at 40% of their initial thickness, (d) rejecting all products having a change of thermal conductivity at 40% compression that is higher than a minimum value of said products by at least 20%, leaving remaining products, and (e) using one of said remaining products as said insulating refractory material.
Claim 29
Dependent Claim
135 words
A process for selecting an insulating refractory material for use in a lining for a container for containing sodium or sodium salts at high temperature, characterized in that said process comprises the steps of: (a) selecting a range of product thermal conductivities having a 20% variation of the values in each range; (b) identifying different insulating products whose room temperature thermal conductivities fall within one of said selected ranges; (c) measuring the percentage loss of room temperature thermal conductivity of all said identified products after compression at 40% of their initial thickness, (d) rejecting all products having a change of thermal conductivity at 40% compression that is higher than a minimum value of said products by at least 20%, leaving remaining products, and (e) using one of said remaining products as said insulating refractory material.
References Cited (Backward Citations)
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