Improvement of the binder system of Refractory Castables with advanced Calcium Aluminate Cements " Authors: Nikolaus Kreuels, Holger Schaffhauser

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1 Improvement of the binder system of Refractory Castables with advanced Calcium Aluminate Cements " Authors: Nikolaus Kreuels, Holger Schaffhauser 1

2 The environment of Refractory Castables" Challenges Potential Answers Increasing Technical challenges Cost reduction in raw materials Ease and robustness of Installation Limited potential Improved properties Market prizes Strength evolution over temperature Refractoriness Slag resistance Flexibility Cost challenges Prize pressure from customers Recycled materials In some application possible Limitation through Technical demands Optimized binder systems In many cases the major cost driver Reduction of CAC through improved binder Decreasing market due to optimized refractory consumption Use of cost optimized CAC 2

3 Two specific elements within Calcium Aluminate Cements Chemistry Mineralogy High Grade 37 % 54 % 64 % Cost Efficient HiPerCem as new CAC focused only on pure Mono Calcium Aluminate to improve castables for challenging applications REFCON plus for cost optimization of standard MCC-LCC-ULCC 3

4 New System for Deflocculated Castables Binder/CAC A shortlist of aggregates Tabular Alumina; WFA; BFA; Spinel, etc. > 98% Al2O3 Regular Castables CAC 80 (CAC 70) Bauxite, Andalusite 60-85% Al2O3 Mullitic Fireclay > 45-70% Al2O3 HiPerCem CAC 70 CAC 70 / HiPerCem and REFCON plus Actual Deflocculated Castables CAC 70 = CAC Standard Fireclay Recyclates > 25 % Al2O3 4 Deflocculated Castables New

5 - COST EFFICIENCY" - BAUXITE - CHAMOTA 44" 5

6 Characteristics Chemical composition, % (ASTM C-114) Production is produced by melting selected raw materials (bauxite and limestone) in special kilns. After cooling, the clinker is ground using ball mills. The total alumina content is adjusted by adding mineral components to enhance peak service temperature performance. Mineral Phases Main mineral phase CA > 60 % Minor mineral phases C 2 AS, CT, C 12 A 7 Physical Data % retained on 325 mesh < 35% Blaine Fineness (ASTM-204) m 2 /kg Bulk density, Powder approx g/ cm 3 Specific gravity g/cm 3 Approximate melting point: 1540 C / 2800 F Quality is tested according to ASTM and other accepted procedures. Quality control data is available for each production lot. The production plant is certified according to EN ISO 9001 certificate number CH08/1542 and the Environmental Management System EN ISO certificate number CH08/1543 6

7 A Mullite Based Aggregate: Mulpeser Mulpeser 60 LN : % HPC 3,5% HPC 5% A 70 Binder (%) HPC 5,0 % 3,5 % Chemical composition of Aggregates A 70 5,0 % CA content 4,8 % 3,3 % 2,9 % CaO content 1,7 % 1,2 % 1,5 % Fines (%) MS 955 U 4,0 % 4,0 % 4,0 % Aggregates (%) GKE-MF 11,0 % 12,5 % 11,0 % Mulpeser 60 DIN 70 15,0 % 15,0 % 15,0 % Mulpeser ,0 % 20,0 % 20,0 % Mulpeser ,0 % 12,0 % 12,0 % Mulpeser ,0 % 33,0 % 33,0 % % Mulpeser 60 Chamota 44 Al 2 O 3 60,6 45,2 SiO 2 33,7 49,9 Fe 2 O 3 1,4 1,2 TiO 2 2,5 3,0 CaO 0,2 0,2 Na 2 O 0,2 0,06 K 2 O 0,06 0,1 Subtotal Aggregates (%) 95,0 % 96,5 % 95,0 % Admixtures (%) Water Addition (%) Budit 4 H 0,10 % 0,10 % 0,10 % 6,0 % 5,9 % 6,0 % Two different HiPerCem additions A 70 at a similar level of CA as 3,5 % HiPerCem Same admixture: Hexametaphosphate with ph: 4 Similar water addition 7

8 Physical Properties: Cold Crushing Strength - Mulpeser At similar content of CAC HiPerCem has higher strengths at lower temperatures Even with only 3,5% HiPerCem green strength, resp. dried strength are at same level or higher After firing HiPerCem and A 70 correspond with CCS It can be assumed from the Bauxite test series, that RuL for HiPerCem is definitively higher as CaO is lower 8

9 Formulations: ULC Bauxite Castable ULC Castables Bauxite A 70 ISTRA 50 REFCON Plus A 70 3,5 % ISTRA 50 3,5 % REFCON Plus 3,0 % * 70A: Reference CAC with 70% Al2O3 * MAC A: Standard Medium Alumina Cement * REFCON Plus New MAC for deflocculated Castables CA content 2,0 % 2,3 % 1,8 % CaO content 1,1 % 1,3 % 1,0 % Fines (%) MS 955 U 4,0 % 4,0 % 4,0 % GKE MF 8,5 % 8,5 % 9,0 % Bindersystem(%) Binder Content 16,0 % 16,0 % 16,0 % Aggregates (%) Bauxite <0,09 14,0 % 14,0 % 14,0 % Bauxite ,0 % 12,0 % 12,0 % Bauxite 1-6 mm 48,0 % 48,0 % 48,0 % Bauxite ,0 % 15,0 % 15,0 % Bauxite ,0 % 33,0 % 33,0 % " Comparison of different additions of CAC 70 " MAC-A = Medium Alumina Cement as comparison " REFCON Plus: " Water adapted for flow app. 210 mm " Admixture as composite for safe rheology control ( influence of Andalusite Andalusite ,0 % 10,0 % 10,0 % Total 100,0 % 100,0 % 100,0 % Admixtures (%) B 6 H 0,10 % 0,10 % 0,10 % STTP 0,05 % 0,05 % 0,05 % Water (%) 5,5 % 5,8 % 5,8 % 9

10 Flow and Flow Decay Flow CAC - Bauxite A ISTRA 50 REFCON Plus CAC (%) A 70 3,5 % ISTRA 50 3,5 % REFCON Plus 3,0 % CA content 2,1 % 2,3 % 1,8 % CaO content 1,0 % 1,3 % 1,0 % Water (%) 5,5 % 5,8 % 5,8 % 5 min Flow (mm) 15 min min Δ Flow -2 % -5 % -2 % " Water addition for all mixes below 6 % and with good early flow " The flow decay is with 1-2 % very good " Slight exception: MAC-A with a Flow decay of 5% " REFCON Plus: Same flow behavior as reference CAC 70 10

11 Setting Characteristics: Ultra Sonic Measurement Potential for Gunning Castables and Precast with REFCON Plus Although REFCON Plus has the same flow behavior as the reference, the setting is starting fast with a high early strength development This makes REFCON Plus also very interesting for Gunning applications with sufficient open tim e for compaction and then fast setting 11

12 ULCC Bauxite Castable Cold Crushing Strength/CCS Comparison of " CAC 70 with 3,5 " REFCON Plus: 3 % " ISTRA 50: 3,5% " The evolution of the results are similar to the MoR, except that. " the degradation of strength development is more distinct with the high cement addition " after C there is a difference of at least > 20 MPa between HiPerCem/REFCON Plus and A 70 " REFCON Plus has with 162 MPa the highest strength level 12

13 ULCC Bauxite Castable Refractoriness under Load/RuL Why is REFCON Plus an engineered CA-Cement? Although 20% lower in Alumina it shows the same hot properties as a CAC 70% " The RuL graph shows the distinction between a 70% CAC (A 70), a standard CAC 50 ( MAC_A) and REFCON Plus has a lower expansion than the A 70 ( 0,6% vs. 1,1%) but reaches this peak at the same temperature" " The subsequent shrinkage has the same tendency for both cements although there is a difference of 20 % Al2O3" " In the comparison with a MAC_A shows a clear advantage for REFCON Plus as the MAC_A retracts much faster than REFCON Plus " HiPerCem, however, remains first choice for challenging applications " 13

14 Formulations: ULC Dense Recycled Porcelain Castable " Comparison of different additions of CAC 70 in a ULCC based on recycled dense Porcelain " Two different Fines have been checked: Bauxite/ Fireclay 45% Al2O3 " MAC-A = Medium Alumina Cement as comparison " REFCON Plus: " Water adapted for flow app. 210 mm " Admixture as composite for safe rheology control ( influence of Andalusite LN : ISTRA 50 REFCON Plus_B A 70_B CA content 2,7 % 2,4 % 2,3 % CaO content 1,5 % 1,4 % 1,2 % MAC-A 4,0 % REFCON Plus 4,0 % A 70 4,0 % Subtotal Cements (%) 4,0 % 4,0 % 4,0 % Elkem 955 U 4,0 % 4,0 % 4,0 % NO 115 TC 12,0 % 12,0 % 12,0 % Bauxite DIN 70 15,0 % 15,0 % 15,0 % Subtotal Fines (%) 31,0 % 31,0 % 31,0 % Dense Porcelain ,0 % 20,0 % 20,0 % Dense Porcelain ,0 % 12,0 % 12,0 % Dense Porcelain ,0 % 33,0 % 33,0 % Subtotal Aggregates (%) 65,0 % 65,0 % 65,0 % Budit 6 H 0,05 % 0,05 % 0,05 % Subtotal Admixtures(%) 0,05 % 0,05 % 0,05 % Total 100,05 % 100,05 % 100,05 % Water/% 6,30 % 6,30 % 6,30 % Indices: * Appendices: * *B: Bauxite Fines * MAC A: Standard Medium Alumina Cement * REFCON Plus New MAC 14

15 Setting Characteristics: Ultra Sonic Measurement REFCON Plus and HiPerCem with Porcelain as Aggregate and Fireclay Fines < 90 µm Potential for Gunning Castables and Precast with REFCON Plus " The comparison shows at app. 45 min a start of set for REFCON Plus followed with the start of set of HiPerCem at 180 min. " Fast strength evolution compared to HiPerCem 15

16 ULCC Recycled Porcelain Castable Cold Crushing Strength CAC Addition: 4 % Fines < 90µm: Bauxite " REFCON Plus develops its strength continuously over temperature " After C highest strength for Refcon Plus 16

17 Formulations: ULC Chamota 44 Castable LN : REFCON Plus-HPC- plus 5% HPC-XR10 PLA5 Ref REFCON Plus, PLA5 plus XR 10 Ref REFCON Plus - B4H plus B4H REFCON Ref Plus,PLA5- plus XR10-CA Refcon Plus 5,0 % 5,0 % 5,0 % 5,0 % HPC 5,0 % CA content 8,1 % 3,3 % 3,3 % 3,3 % CaO content 3,5 % 1,8 % 1,8 % 1,8 % Subtotal Binder (%) 10,0 % 5,0 % 5,0 % 5,0 % MS 955 U 4,0 % 4,0 % 4,0 % 4,0 % GKE-MF 11,0 % 11,0 % 11,0 % 11,0 % Chamota 44 DIN % 15,0 % 15,0 % 15,0 % Chamota ,0 % 20,0 % 20,0 % 20,0 % Chamota ,0 % 12,0 % 12,0 % 12,0 % Chamota ,0 % 33,0 % 33,0 % 33,0 % Subtotal Aggregates 95,0 % 95,0 % 95,0 % 95,0 % B 4 H 0,10 % PLA5 XR10 0,10 % 0,10 % 0,10 % Citric Acid 0,02 % Subtotal Admixtures 0,10 % 0,10 % 0,10 % 0,12 % Chemical composition of Aggregates % Mulpeser 60 Chamota 44 Al 2 O 3 60,6 45,2 SiO 2 33,7 49,9 Fe 2 O 3 1,4 1,2 TiO 2 2,5 3,0 CaO 0,2 0,2 Na 2 O 0,2 0,06 K 2 O 0,06 0,1 " Influence of RECFON plus with difference admixtures " Special development for extended working time: 7,4 % 7,3 % 7,6 % 7,6 % 17

18 Setting Characteristics: Ultra Sonic Measurement Extended working time with XR 10 18

19 Physical Properties: Cold Crushing Strength Chamota Aggregates exhibits with the new admixture a sufficient strength level with good intermediate strengths The addition of HiPerCem in this case leads to high strengths at low temperatures 19

20 Conclusion" HiPerCem High CAC focused on 95% reacxve Mineral mono Calcium Aluminate Improved ParXcle Size DistribuXons and Specific Surface Improved mechanical strength with all raw materials tested Superior hot properxes as Hot Modulus of Rupture and Refractoriness under load Engineered Medium Aluminate Cement for higher cost efficiency Good physical properxes Very good high temperature properxes Together with adapted admixture system workability is easy to adjust Flexibility for gunning and casxng 20

21 Thank you for your acenxon All the information provided is in accordance with the present state of our knowledge. It is based on our laboratory experience using raw materials indicated in the presentation. Nonetheless, we disclaim any warranty or liability for the data and formulations presented.