Refractories and Industrial Ceramics

Vol. 52, No. 2, July, 2011

RAW MATERIALS HIGH-ALUMINA TECHNOGENIC RAW MATERIAL V. A. Perepelitsyn,1 V. A. Koroteev,2 V. M. Rytvin,3 S. I. Gil’varg,4 V. G. Grigor’ev,4 V. G. Ignatenko,3 A. N. Abyzov,3 and V. G. Kutalov5 Translated from Novye Ogneupory, No. 4, pp. 23 – 27, April 2011.

Original article submitted February 8, 2011. The substance composition, properties, and areas for use of five large scale varieties of technogenic high-alumina mineral raw materials are considered: aluminothermal slags, organic synthesis catalysts, abrasive slurries, aluminium slags and alumina dust. With combined use on the basis of this secondary raw material it is possible to produce more than twenty forms of different product: refractories, ceramics, abrasives, cement, slag neutralizers, fluxes, proppant sands, glass fiber, sitalls, coagulants, pigments, etc. Keywords: mineral composition, chemical composition, microstructure, wastes, slag, slurry, dust, alumina, corundum, spinel.

catalyst production or synthetic rubber (65 – 75), corundum slurry from abrasive production (82 – 96), dust from alumina calcining furnaces (90 – 97), and metal-mineral waste from the production of secondary aluminum (60 – 72). Technogenic “deposits” are primarily a potential raw material for synthesis of refractories, heat-resistant, and ceramic fuzed materials of different composition: alloyed corundum, mullite-corundum, spinel, codierite, etc. In view of the wide range of mechanical, thermal and chemical properties many varieties of technogenic mineral raw materials may be used effectively, not only in the refractory branch, but also in the production of abrasives, binders, heat insulation and other functional materials and objects [1 – 3]. In order to develop effect areas for recycling secondary mineral resources complete information si necessary about the substance, grain size composition and physicochemical properties of each variety of technogenic polyphase and often polydispersed technogenic raw material.

Currently in the Ural region a number of scientific organizations and industrial enterprises are participating in the fulfilment of Regional and Federal programs for processing technogenic formations. In 2008 the presidium of the Russian Academy of Sciences developed and approved a comprehensive program for study and assimilation of untraditional sources of mineral raw material, including technogenic formations. Main attention in the academic program is devoted to high-alumina natural and technogenic raw material sources: minerals of the kyanite, andalusite, silimanite, kaolinite and pyrophilite groups, aluminosilicate waste from thermal power engineering, high-alumina slags, slurries, dust, etc. Within the scope of fulfilling these programs there is research work, a study of substance composition and properties of mineral raw materials, and promising areas are being developed for use of the most valuable varieties of technogenic high-alumina materials. Among the latter are the following large-scale technogenic formations are of greatest practical interest (limits of Al2O3 content, wt.%, are shown in brackets): aluminothermal slags in the production of the majority of ferroalloys and master alloys (50 – 85), wastes of 1 2 3 4 5

ALUMINOTHERMAL SLAGS FROM FERROALLOY AND MASTER ALLOY PRODUCTION

OAO VOSTIO, Yekaterinburg, Russia. Institute of Geology and Geochemistry UrO RAN Yekaterinburg, Russia. OOO Klyuchev Enrichment Plant, Dvurechensk, Sverdlovsk Region, Russia. OAO UK RosStetsSplav, Yekaterinburg, Russia. OOO NPO VOSTIO, Yekaterinburg, Russia.

OAO Klyuchev Ferroalloy Plant is the sole enterprise in the RF and CIS producing more than thirty named unique ferroalloys and master alloys by the method of aluminothermal reduction of metals from oxides and other com84 1083-4877/11/05202-0084 © 2011 Springer Science+Business Media, Inc.

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pounds. Aluminothermal reduction of metals from oxides occurs by the following chemical reaction:

and ferrochromium, which is total is about 89%. Apart from different slags, stored in the dump, the yearly volume of slag from current production is 20 – 30 thousand tons.

2/m MenOm + 4/3Al ® 2n/m Me + 2/3Al2O3. In view of this in contrast to all of the other slags of ferrous and nonferrous metallurgy the chemical base of aluminothermal slags (ATS) is alumina, whose average content as a rule exceeds 50% (Table 1). For almost seventy years of the history of functioning of the plant a considerable slag dump has been formed, which in the opinion of specialists [4] is the best technogenic deposit of the Urals, containing semifunctional raw material. The overall reserve of slag in the dump is about 2.5 million tons. Approximately, according production statistics data, the distribution of slags with respect to form of alloys is provided in Table 2 [5]. Within the dumped mix there is clearly a predominance of slag from production of ferrotitanium, chromium metal

Titanium-Alumina Slag The main quality criterion for mineral raw material, on which a number of its functional properties prominently depend, is the amount of quantitative mineral composition [6]. The mineral composition of slags from ferrotitanium production is provided in Table 3, which in view of the specific chemical composition and production practice have been given the name titanium-alumina slags. Dumped slags produced in the 1940 – 50s contain corundum and bonite, more basic calcium aluminates are absent or contained in a small amount, exceptionally in the form CaO·Al2O3 (calcium dialuminate). In a later period and currently, as a result of a change in raw material composition

TABLE 1. Average Composition of OAO Klyuchev Ferroalloy Plant Slags Content, % Alloy

Chromium: metal metal (low-nitrogen) refined Carbon-free ferrochromium Cr–Nb–Ni master alloy Low-silicon ferroniobium Ni–Nb master alloy Ferroaluminozirconium Ferrosilicozirconium Ferrotungsten* Ferrotitanium single-stage two-stage

Al2O3

SiO2

CaO

FeO

MgO

Cr2O3

TiO2

Nb2O5

ZrO2

78.6 76.5 70.5 58.0 75.5 71.0 65.0 53.5 56.0 62.0

0.26 0.1 0.1 0.55 0.1 0.3 — 0.6 2.3 0.7

9.7 11.2 12.5 16.7 20.5 20.0 — 25.0 24.0 36.0

0.3 0.4 0.2 0.5 0.6 1.3 — 0.4 0.4 0.5

1.8 0.3 0.8 13.5 1.0 5.4 — 3.1 3.6 —

6.9 9.4 13.0 7.5 1.3 — — — — —

— — — — — — — — — —

— — — — 0.24 0.9 0.7 — — —

— — — — — — — 10.0 10.5 —

71.5 71.0

0.8 0.8

14.0 17.0

0.6 0.6

3.1 3.0

— —

8.0 7.0

— —

— —

* Contains 0.2 wt.% WO3.

TABLE 2. Distribution of Slags in Dump According to Form of Alloys Material

Mixture of slags and hard alloys Slag from production: ferrotitanium (and alloy inclusions) chromium metal (and alloy inclusions) ferrochromium (and alloy inclusions) low-silicon ferroniobium ferrosilicozirconium (and alloy inclusions) ferrotungsten Slag remnant and alloy inclusions Ferrous metal scrap (rough) Broken refractories and carbon lining, material remnants

Weight fraction, %

Amount, thou. ton

100

2500

42 33 14 6.5 1.7 0.8 0.7 0.2 0.8

1050 825 350 162.5 44 20 17.5 5 20

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TABLE 3. Mineral Composition of Titanium-Alumina Slags Content of minerals (compounds), wt.% Sample corundum bonite spinel CaO·2Al2O3 CaO·Al2O3 TiO + Ti2O3 + TiO2 (Al,Ti)2O3 CaO·6(Al,Ti)2O3 Mg(Al,Ti)2O4

perovskite ferrotitanium CaTiO3 FemTin

1

5.8 – 52.7

16.4 – 83.2

—

—

9.4 – 25.4

1.6

—

2 3 4 5*

5–6 — — —

72 – 73 40 – 55 35 – 40 35 – 40

7–8 15 – 20 20 – 25 30 – 35

– 5 – 15 8 – 10 8 – 10

6–7 8 – 15 5–8 4–6

– 5–7 8 – 10 8 – 10

5–7 — 20 – 25 15 – 20

rest

0.06 – 5.72 CaS 0.3 – 0.8; TiN 1.73; CaF2 1.48 – – — — 1–2 — <0.5 —

Information source

[7]

[8] [9] [10] [10]

* Slag of current production, rest of the slag samples produced in the period 1948 – 1988.

and ferrotitanium production technology, the mineral composition of the slags has become markedly complicated and includes more than five compounds, predominantly from the class of complex oxides: calcium aluminates, spinel and perovskite. Apart from ferrotitanium and independent titanium oxides in the from of an isomorphous admixture there are bonite and spinel within the composition. The refractoriness of titanium-alumina slags in relation to chemical and mineral composition is 1550 – 1630°C. They may be used as fillers for heat-resistant concretes with a service temperature up to 1400°C [11]. Titanium-alumina slags, containing up to 20% titanium (converted to TiO2), are a promising technogenic (“ore”) raw material for preparing titanium and its compounds. Here extraction of the metal phase, i.e., ferrotitanium, exhibiting magnetic susceptibility, may be accomplished by magnetic separation. On the basis of titanium-alumina slags of limited industrial production there is series of alumina-cement clinkers with a content of 50 – 60% Al2O3 (grades KGTs-15 and KGTs-60). The most effective area for use of ferrotitanium slag in refractories, even in the 1950s, was developed in UkrNIIO. In essence it involved the fact that in view of an increased Al2O3 and TiO2 content the slag is an effective mineralizer and a starting component for the production of magnesia-alumina spinel, dense periclase objects and other products [12 – 14]. We have established the fundamental possibility of using titanium-alumina slag in blast furnace production, and in fact as a component for forming a protective titanium carbonitride skull on the working surface of a blast furnace hearth and bottom [5]. A traditional area for recycling titanium-alumina slag in ferrous metallurgy is use as a semifinished product for melting synthetic slags, used for steel refining. For nonferrous metallurgy, in particular for preparing alumina, these slags a new promise of secondary mineral raw material together with bauxite and nepheline. In OAO VAMI the main production parameters have been developed for comprehensive reprocessing of titanium-alumina slag in the production of alumina by sintering [15].

Chromium-Alumina Slags These slags are a subsidiary product, i.e. production waste from chromium metal and ferrochromium production by the aluminothermal method. Chromium metal slag of current production and stored in a dump has high strength (sco up to 200 MPa) and a monolithic microstructure. Ferrochromium ATS gave two varieties: monolithic (strong rock) and fine-grained (powder). The mineral composition of chromium-alumina ATS is provided in Table 4. The mineral basis of chromium metal slags from dumps of current production is three minerals (compounds): chromium corundum (rubin), chromium bonite CaO·6(Al,Cr)2O3, and chromium containing b-alumina Na2O·11(Al,Cr)2O3 with a melting temperature of 2050, 1850 and 2000°C respectively. Due to this the composition of these slags among ATS has the highest refractoriness (1750 – 1900°C) [3, 11, 13]. The mineral composition of monolithic ferrochromium ATS is distinguished from all others by predominance in the composition of chromium-containing spinel Mg(Al, Cr)2O4 in combination with high-alumina calcium aluminates 12CaO·7Al2O3 and CaO·Al2O3, which have relatively low melting temperature (1450 – 1700°C), but exhibit high hydraulic activity. Powder ferrochrome ATS, apart from spinels, contain a significant amount of bicalcium silicate of g-modification (g-2CaO·SiO2, analog of the natural mineral shannonite). The reason for the arbitrary decomposition of this ATS and conversion of it into granular powder is polymorphic transition of high-temperature modification of b-Ca2SiO4 into low-temperature g-Ca2SiO4, accompanied by an increase in volume by 11.5% during slag cooling [17]. Arbitrary decomposition of ferrochromium slag only occurs with observation of two conditions: a basicity CaO/SiO2 less than 1.8 and a content of calcium orthosilicate not less than 10%. An area of recycling for the three varieties of chromium-alumina slag is determined by chemical, but exclusively by the actual mineral (phase) composition. Highly refractory ATS minerals of chromium metal have provided for

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more than forty years the possibility of its use as a replacement for fuzed alloyed corundum for the production of high-alumina refractories, refractory concretes and mixes [18 – 21]. The slag is also a commercial alumina product for manufacturing high-alumina cements KVTs-70, KVTs-75 (Table 4), slag-forming mixes, abrasive powders, corrosive slag neutralizers and other products [5, 11]. Currently in order protect refractory lining of vacuum equipment connecting pieces from corrosive action of ladle slags there is use of corundum neutralizer grade MKNF with an Al2O3 content more than 90 wt.%, and a cost above 30 thousand rubles per ton. Colleagues of OAO GNTs Ural Institute of Metals and OAO MTMK have performed successful tests for the use of high-alumina ATS instead of expensive corundum nuetralizer. Use of high-alumina ATS compared with a corundum neutralizer showed the following advantages: – a reduction in specific expenditure for refractories and neutralizer by 22 and 68% respectively; an increase in lining life by 8 – 10%; – improvement of steel quality due to a reduction in sulfur and non-metallic inclusion content. Thus, under industrial conditions adequate efficiency has been confirmed for use of ATS, whose cost is almost an order of magnitude lower than for corundum compound neutralizer [15].

The high refractoriness of chromium metal ATS makes it possible to use it in refractory objects and concretes for replacing such expensive and scarce raw materials as corundum, aluminum hydroxide, technical grade alumina, low-iron bauxite, and high-alumina refractories. Slag concretes based on refractory ATS are used extensively in lining various heating units of ferrous and nonferrous metallurgy and in the chemical industry, in furnace for firing ceramic objects, in glass melting furnaces, for lining thermal power station boilers, preparation of the hearth of heating furnaces and soaking pits, casting molds, and burner stones. A common property of chromium-alumina ATS is aluminophobicity, i.e. a capacity not to be wetted by molten aluminum, alloys based on it, and not to enter into reaction with it [22 – 24]. Results of industrial tests of slag cement in OAO Vtortsvetmet have shown absence of wetting and impregnation of a lining by molten nonferrous metals and alloys. Thus, in contrast all varieties of natural and technogenic minerals raw material ATS have a unique combination of substance composition, microstructure and physicochemical properties, which makes it possible to produce a broad range of products based upon them: refractories, heat-resistant cements and concretes, refining slags, metallurgical fluxes, and other valuable materials.

TABLE 4. Mineral Composition of Main OAO KZF Chromium-Containing Slag Materials Content of minerals and compounds, wt.% chromium corundum (Al,Cr)2O3

chromium bonite CaO·6(Al,Cr)2O3 + chromium b-alumina (Na,K)2O·11(Al,Cr)2O3 (total)

calcium dialuminate CaO·2Al2O3

calcium monoaluminate CaO·Al2O3

maienite 12CaO·7Al2O3

chromium spinel Mg(Al,Cr)2O4

30 – 35

55 – 60

3–4

—

3–4

3–4

—

dumped

15 – 20

65 – 70

4–5

—

2–3

2–3

—

The same

35 – 40

—

—

—

0.8 – 1.0

—

The same

1–7

55 – 60 (b-alumina) 45 – 55 (bonite)

30 – 35

—

—

10 – 15

1–2 (glass)

Melted metal or alloy

Chromium metal: current (PG-75)

Ferrochromium: dumped*1 The same current monolithic (ShFKh-A) current self-decomposing (ShFKh-AS)** High-alumina cement clinker (KVTs-75)

merwinite metal phase Ca3Mg (composition) (SiO4)2

—

—

—

—

28.4

54.8

—

—

—

30 – 35

8 – 10

55 – 60

8.9 (glass) —

—

—

—

15 – 20

12 – 17

60 – 65

—

—

—

—

3–4

2–3

55 – 70

3–5

—

3–5

65 – 70

20 – 25

—

1–5

—

* Contains 5.6 wt.% periclase. ** Contains 20 – 25 wt.% shannonite g-Ca2SiO4 and 2 – 4 wt.% periclase.

Information source

1–2 Authors of (Cr) article [3] 1–2 [3] (Cr) 1–2 [16] (Cr) 0.5 – 1.0 [16] (glass) 2.0

[16]

2–3 (FeCr) 5–7 (FeCr) 2–3 (FeCr) 0.1 – 0.5 (FeCr)

[3] [17] [17] [10]

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V. A. Perepelitsyn et al.

ALUMINOCHROMIUM CATALYST WASTE Aluminochromium catalyst (ACC) waste forms in large volumes in the production of synthetic rubber, and in enterprises of the petrochemical industry. According to a rough OAO VOSTIO estimate, enterprises of this branch yearly produce 30 – 50 thousand tones of exhausted catalyst grade IM-2201 in the from of dry powder, granules and slurry. According to technical specifications TU 2173-01073776139–2009. this material is called “dialuminum trioxide catalyst with dichromium oxide impurity.” It is a fine powder of gray-green color with a bulk density of 1.0 – 1.5 g/cm3 containing not less than 60% Al2O3 and not more than 10,5% SiO2. The chemical and grain size composition of ACC waste of the leading Russian producer enterprises is provided in Table 5. The mineral (phase) composition of ACC, determined by x-ray phase and petrographic analyses, is mainly corundum a-Al2O3 and the gamma-modification of alumina (g-Al2O3),

Fig. 1. Particle dimensions of ZAO Kauchuk catalyst IM-2201.

and also chromium oxide (a-Cr2O3) that is the structural chemical artificial analog of the natural rare mineral escolite. It has in a relatively small amount amorphous silicon dioxide (SiO2), i.e., also an analog of the rare mineral lechatelierite, and quartz. An example of the quantitative composition is as follows, %: corundum (a-Al2O3) 30 – 60, alumina (g-Al2O3) 20 – 40, escolite (a-Cr2O3) 12 – 15, lechatelierite (SiO2) 5 – 7, quartz (b-SiO2) 4 – 5, and clay 1 – 3. ZAO Kauchuk (Sterlitamak) exhausted catalyst consists of fine particles with an average size of 1.1 – 2.4 mm (Fig. 1). In grain size composition this is mainly similar to technical grade alumina, within which more than 80% of particles have a size of less than 90 mm. The catalyst has a bulk density of 1.0 – 1.4 g/cm3, true density (specific gravity) 3.45 – 3.47 g/cm3, refractoriness 1900 – 2000°C. On heating ACC to 1600°C in an oxidizing atmosphere chromium oxide is entirely dissolved in the corundum crystal lattice, silica and other impurities (R2O, RO) converted into a glass phase. The most complete use of ACC for producing spinelid, high-alumina and magnesia spinelid objects was carried out in the 1970s in UkrNIIO [25 – 27]. The effect of additions of magnesite (periclase) [powder in an amount from 10 – 80% on sintering and properties of synthesize spinelid (Table 6) and determination of the phase (mineral) composition of these specimens after firing at 1750°C with soaking for 6 h (Table 7) have been studied in detail. As a result of research work production technology has been created for high quality refractory objects, within which

TABLE 5. Properties of Aluminochromium Catalyst IM-2201 Waste Component content, % Fe2O3

CaO

MgO

Bulk density, g/cm3

1.72 0.8 — — £1.3

0.14 0.1 — — £1.5

— 1.6 — — £1.0

1.0 – 1.4 1.43 1.2 1.3 1.1

Enterprise Al2O3

Cr2O3

K2 O

SiO2

PO OAO Nizhnekamsk-Neftekhim* 70 – 75 15.0 3.3 12.0 Tol’yatti OAO Sintezkauchuk 69.0 13.0 1.4 11.0 OAO Novokuibyshev Petrochemical Combine 72.2 – 73.3 14.8 – 15.8 8.8 – 3.56 9.57 – 11.4 OAO Chaikovskii Synthetic Rubber Plant 7.0 14.0 2.5 – 3.5 10.0 ZAO Kauchuk (Sterlitamak) 60 – 75 8 – 20 1.2 8 – 11

* Grain size composition of PO OAO Nizhnekamsk-Neftekhim aluminochromium catalyst IM-2201 waste, %: fraction >0.5 mm 1.48, 0.4 – 0.5 mm 0.98, 0.28 – 0.4 mm 2.02, 0.2 – 0.28 mm 2.0, 0.16 – 0.2 mm 1.52, 0.1 – 0.2 mm 5.26, 0.071 – 0.1 mm 0.34, .071 mm 86.4.

TABLE 6. Effect of Magnesite Powder Addition on Properties of Spinelid Specimens From Waste After Firing at 1750°C [25] Charge composition, % waste

magnesite powder

Apparent density*, g/cm3

90 80 67 53 47 33 20

10 20 33 47 53 67 80

3.13/2.97 2.95/2.86 2.98/2.99 3.05/3.11 3.06/3.10 3.12/3.03 3.13/3.15

Shrinkage* on firing, %

21.5/14.7 18.4/11.9 19.3/16.6 16.3/17.0 16.9/15.2 14.1/11.8 11.7/14.1

Deformation temperate under 0.2 MPa load, °C Thermal shock resistance*, water thermal cycles start of softening 4% compression breakage from 1300°C

1/1 1/1 1/1 9/10 8/10 8/8 7/9

* Numerator is with use of waste fractions finer than 1 mm, denominator is finer than 0.06 mm.

1560 1480 1600 1540 1610 1570 1610

1640 1540 1690 1610 1720 1630 1700

1680 1540 1750 1740 1770 1710 1700

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instead of scare and expensive metal chromite synthetic spinelid is used, i.e. a product of high-temperature solid-phase reaction of ACC with periclase by the reaction

and improved thermomechanical property indices have been prepared. The properties of the “chamotte” and objects based on it obtained are provided in Tables 8 and 9. A study of the possibility of preparing melted material from one ACC of original grain size in an arc furnace of IKB-514 [26] has been studied. The material was melted into a block, had high strength (ultimate strength in compression 340 MPa, temperature for deformation under a load of 0.2 MPa, 1600°C).The chemical composition and property for melted ACC are provided in Table 10. In addition, refractory objects have been prepared from melted material by ceramic technology with the best thermomechanical property indices.

[Al2O3 + Cr2O3] + MgO ® Mg[Al,Cr]2O4 (Tm ³ 2200 °C). ACC Spinelid Silica ACC also react with periclase with formation of secondary (reaction) forsterite: SiO2 + 2 MgO ® 2MgO·SiO2 (Tm = 1890 °C). From ACC With use of ACC for chamotte manufacturing technology high-alumina objects with a content of 72 – 75% Al2O3

TABLE 7. Phase Composition of Mixed Specimens of ACC Waste with Magnesite After Firing at 1750°C [25] Free MgO content, % Amount of magnesite by chemical addition, % calculated composition

10 20 33 47 53 67 80

— — — 20 30 50 70

Phase composition Mg(Al,Cr)2O4

solid solution in corundum-spinel system, %

amount, %

grain size, mm

50 – 55 — — — — — —

30 – 50 — 82 – 85 70 55 – 58 40 25

8 – 15 — 20 – 80 15 – 60 15 – 60 15 – 50 15 – 50

0.20 0.94 0.55 18.95 26.20 47.30 59.49

periclase*, %

solid solution Al2O3–Mg(Al,Cr)2O4**, % forsterite, %

— — — 10 – 12 25 45 63 – 65

— 85 — — — — —

15*** 15*** 15 – 18 18 – 20 18 – 20 15 10 – 12

* Grain size 80 – 120 mm. ** Grain size 8 – 25 mm. *** Amount of glassy substance shown, %.

TABLE 8. Effect of Preparation temperature of Chamotte From ACC Waste on Fired Specimen* Properties [25] Values of property** indices of specimens fired at temperature, °C Properties

Open porosity, % Apparent density, g/cm3 Linear shrinkage, % Ultimate strength in compression, MPa

1550

1650

1750

15.3 – 16.3 22.4 3.03 – 3.06 2.88 2.8 2.8 23.5 49.0

12.7 20.2 3.18 2.95 4.0 2.8 Not det. 62.0

7.6 12.6 3.35 3.18 5.6 4.6 Not det.

1390 Not det. 1520 Not det. 1710 Not det.

1500 1510 1560 1570 1700 1610

1560 1560 1610 1700 1760 1750

Deformation temperate under 0.2 MPa load, °C start of softening 4% compression failure

* Numerator is property indices for specimens based on chamotte, prepared by firing at 1550°C, denominator is based on chamotte, prepared by firing at 1750°C. ** Thermal shock resistance of specimens based on lightly fired chamotte, fired at 1650°C, comprises more than 15 thermal cycles 1300°C – air.

90

V. A. Perepelitsyn et al.

nology is complicated by presence of harmful and toxic components (in some waste).

Thus, as a result of studies and development it has the technical possibilities and economic expediency have been established with use of ACC for manufacturing periclasespinelid, spinelid and high-alumina refractories. According to UkrNIIO data, the cost of ACC is three times lower than scarce and expensive technical grade alumina [26]. In 1983 – 1984 in the Western Institute of Refractories as a result of comprehensive study of various technogenic raw materials work was performed on “Technical and economic evaluation (TEE) of use of industrial waste as raw material for producing refractory materials.” On the basis of the TEE the required assortment and volume of production was determined for new highly effective objects and materials based on ACC. In view of the content in ACC of up to 20% Cr2O3 and a clear shortage of chromite in the RF it is desirable to use aluminochromium catalyst also as a starting raw material for producing chromium, ferroalloys based on it, chromium salts and other products. Apart from ACC many of the chemical industry, just in the Ural region there is formation of a considerable volume (more than 3500 tons/year) of exhausted catalyst, containing more than 80% Al2O3. This waste is only partly used, and therefore it is dumped in an enormous amount in stores and dumps. This considerably exacerbates the ecological problem [28]. Utilization of it in high-temperature material tech-

ABRASIVE PRODUCTION CORUNDUM SLURRIES Electrocorundum slurry is a fine-grained powder formed during crushing and grinding of fuzed corundum in the abrasive industry. The chemical and grain size composition of slurry waste of electrocorundum are given in Table 11. The substance composition of slurry waste shows presence of all varieties of fuzed corundum: white, normal, titanium, chromium, etc. In view of the high Al2O3 content (85 – 98%) and the fuzed microstructure of particles this material is a valuable semifunctional secondary mineral raw material for producing refractories, ceramics, proppant sands, refractory fiber, high-alumina cement, slag neutralizers, abrasives and other products. There are numerous publications about the use of corundum slurries for producing high-alumina and aluminosilicate refractories, author’s testimonies for inventions and patents. The most significant volume of research in this area was carried out by the branch industries of the Ural region: UralNIIstromproekt [29], VoctIO [30], BashNIPIstrom [31], etc. In spite of the adequate scientific and technological level of the research, possibilities of using electrocorundum slag in manufacture from many forms of product, it has not been

TABLE 9. Properties of High-Alumina Objects from ACC waste [25] Values of property indices for specimens fired at temperature, °C Properties

Open porosity, % Apparent density, g/cm3 Linear shrinkage, % Ultimate strength in compression, MPa Deformation temperate under 0.2 MPa load, °C: start of softening failure Additional shrinkage at 1600°C and 2 h soaking, % Thermal shock resistance, thermal cycles from 1300°C: water air

1580

1650

21.0 2.84 – 2.86 1.7 – 2.5 47 – 55

17.6 – 18.5 2.98 – 3.04 3.2 – 4.4 70 – 116

1520 1680 0.2

1600 17 0*

2 Not det.

2 4

* Additional shrinkage at 1700°C 0.6 – 0.7%.

TABLE 10. Properties of a Melted ACC Block [25] Sample selection location

Upper surface of block central part Middle of block Lower surface of block central part Side surface of 400 ´ 400 mm2 face Side surface of 400 ´ 700 mm2 face

Open porosity, %

Apparent density, g/cm3

0.97 2.10 1.30 2.90 1.90

3.40 3.46 3.44 3.42 3.50

Chemical composition*, % Al2O3

SiO2

CaO

MgO

Cr2O3

FeO

81.34 83.37 81.79 81.70 82.59

5.80 4.72 5.52 5.36 5.24

0.66 0.31 0.72 0.43 0.42

9.62 9.53 9.52 9.62 9.72

2.72 2.18 2.47 3.15 2.47

0.22 0.23 0.22 0.23 0.22

* Chemical composition of waste, taken for melting, %: Al2O3 78.13, SiO2 6.44, Fe2O3 0.36, CaO 0.75, MgO 0.2, Cr2O3 13.11.

High-Alumina Technogenic Raw Material

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found industrial scale application. This is mainly explained by two factors. Fist, wastes in abrasive plants are in the form of wet slurries, and delivery of them to refractory enterprises is complicated, particularly in the winter period when they freeze. Second, there are no free specialized production areas for manufacturing products based on this waste. The annual volume of electrocorundum waste formed is about 20 thousand tons. Reserves of electrocorundum slurry are not considered entirely since there is no information about the amount of slurry in large enterprises of basic production, for example OAO Chelyabinsk Abrasive Production Plant. The quality of electrocorundum slurry is controlled by specification TU 2 – 107–79 “High-alumina product for synthetic slags,” developed by the VNIIASh Institute and the Yurgin Abrasive Plant. In accordance with these technical specifications corundum slurry waste should contain %: Al2O3 not less than 85.0; SiO2 not less than 2.0, TiO2 not more than 2.0; Fe2O3 not more than 1.6, moisture content not more than 2.0. On the basis of developments and industrial tests OAO VOSTIO recommends use of electrocorundum waste to be used to produce five forms of refractory product: synthetic mullite-silica objects (TU 14-8.207–76) at 60 thousand tons/year, weight of quartz corundum composition, 15 thousand tons/year, periclase-alumina-chromite mix, five thousand tons/year, aluminosilicate plastic mixes according to TU 14-8-308–79 grades MShPB, MKLBP, MMLBP, ten thousand tons/year, and ramming mix, ten thousand tons/year. The overall planned annual volume of refractory products is 100 thousand tons.

SECONDARY ALUMINUM PRODUCTION WASTE In nonferrous metallurgy plants during the production of secondary aluminum and alloys based on it there is formation in significant volume of both so-called aluminum slag (AS). The AS chemical composition of several RF enterprises is provided in Table 12. Slag is processed in liquid form, by a dry method, and by leaching [32]. Most often processing is carried out by the dry method (Fig. 2), by crushing, grinding and screening. After screening the dust fraction, captured in cyclones, is hardly used and is moved to dumps. In large fractions there is concentration of aluminum metal (60 – 80%), which is subject to melting as charge component. X-ray phase and petrographic analyses have established that the mineral (phase) composition of AS is a mixture of minerals of various chemical classes: simple oxides (corundum, a-Al2O3, and gamma-alumina g-Al2O3), complex oxides (bonite CaO·6Al2O3 and b-alumina (N,K)2O·11Al2O3), spinel MgAl2O4, hydroxides (bayerite, Al(OH)3), chlorides (halide NaCl and sylvite KCl), nitrides (AlN), silicates, glass phase, etc. (Table 13). The true (pycnometric) density of AS after removing the aluminum metal is 3.3 – 3.5 g/cm3, the bulk density is 0.7 – 0.8 g/cm3, and refractoriness is 1450 – 1530°C. The relatively low refractoriness of AS is due to the increased content of readily-melting sodium and potassium chlorides with a melting temperature of 801 and 776°C respectively. The overall content of these chlorides reaches 25%. It is possible to remove these chlorides by hydro-

TABLE 11. Chemical and Grain Size Composition of Slurry and Other Forms of Electrocorundum Waste Content, wt.%, fractions, mm

Component content, wt.% Enterprise

Al2O3

Fe2O3

OAO Chelyabinsk Abrasive 3.5 ³85.5 production Company OAO Yurginsk Abrasive Plant 90 – 96 0 – 1.8 OAO Volga Abrasive Plant £85.0 £5.0 OAO Kyshtym Abrasive 92.0 – 98.0 2.9 – 1.0 Material Plant

SiO2

TiO2

Cr2O3

CaO + MgO

£2.0

£4.5

—

4.0 (1.0)*

5.0

1.0 75.0

0 – 1.5 — —

0 – 0.6 £1.5 1.0 – 0.5

3.0 — —

— — —

0 – 0.06 0 – 1.5 — £10.0 3.0 – 0.3 1.5 – 2.5

160 500 <40

— — —

<63

>80

<80

—

—

—

Slurry moisture content, %

18.0

67.0 — — — — — — — — 10 – 6 90 – 94 35 – 40

* MgO content shown in brackets.

TABLE 12. Chemical Composition of Secondary Aluminum Production Waste Component content, % Enterprise Na2O

Cl

å MeCl

Al

Al2O3

MgO

SiO2

CaO

Fe2O3

K2 O

A B C D

10 – 18 26.5 2.7 4.8

50 – 74 36.3 43.9 15.9

3–8 1.7 9.3 1.2

2–4 5.9 2.6 1.4

2–3 3.2 0.8 2.4

E

4–7

40 – 68

4 – 10 8.5 4.9 Not determined 7.2

3.6

2.0

1.9

Not determined 12 – 15 The same 5.8 1.9 3.9 Not determined 5.5 34.2 33.0 Not determined Not determined 10 – 13

Dmcal

14.0 9.8 11.2 15.8 10.9

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V. A. Perepelitsyn et al.

Fig. 2. Production scheme for processing dumped slag by dry method [32].

metallurgical or pyrometallurgical methods [32]. With aqueous leaching of AS it is possible to prepare material with chloride-ion Cl- content less than 0.5% and total alkali oxides Me2O less than 3% [33]. This high content of these impurities in the material is impermissible with use of it as a raw material for producing magnesia refractories and technical grade alumina. It is possible to remove alkali oxides by thermochemical treatment of AS by firing in a mixture with caustic magnesite (more than 25%) at 900 – 1300°C [33]. With a further increase in temperature (up to 1600°C and above) in this mixture spinel MgAl2O4 is synthesized, which may be used in the production of periclase-spinel objects. AS, containing up to 70% Al2O3 and currently stored in the main dumps, is promising technogenic semifunctional raw material for producing not only refractories, but also other products. Favorable results have been obtained with partial replacement of bauxite by this slag in a charge for preparing alumina cement. The possibility has been revealed of using AS as a combined addition in the production of cellular concrete and preparation of aluminium-containing coagulant for cleaning sewage. A significant volume of AS may be utilized in technology for special and high-strength ceramics, for example proppant sands of corundum-spinel composition [34]. Promising areas are known for recycling AS in metallurgy as a raw component for preparing aluminum-containing ferroalloys [35], slag-forming and exothermic mixes, thermite briquettes, magnesia fluxes and other products. Thus, the comprehensive use of AS will make it possible to produce a broad range of different products with total or partial replacement of expensive and scarce raw materials, i.e., alumina and aluminum. ALUMINA CALCINING FURNACE DUST

TABLE 13. Minerals Within the Composition of Secondary Aluminum Production Waste Compound

Corundum Gamma-silica Aluminum Halite Sylvite b-alumina Bonite Gibbsite Quartz Carbon Bayerite Spinel Aluminum nitride Glass phase Periclase Aluminum carbide

Chemical formula

Melting temperature, °C

a-Al2O3 g-Al2O3 Al NaCl KCl (Na,K)2O·11Al2O3 CaO·6Al2O3 Al(OH)3 SiO2 C Al(OH)3 MgAl2O4 AlN Me2O–MeO–Al2O3–SiO2 (complex system) MgO Al4C3

2050 2050 660 801 776 ~2000 1850 2050 1713 4500 2050 2135 2200 £1000 (softening) 2800 2200

Technology for preparing aluminum metal includes heat treatment of semifinished product, i.e., aluminum hydroxide in rotary furnaces at a maximum temperature of 1300 – 1500°C. Firing of powder charges is accompanied by formation of a considerable amount of dust, which is captured in electric filters. Dust from alumina calcining furnaces is a finely dispersed powder (up to 80% fraction <10 mm), containing wt.%: Al2O3 90 – 96, SiO2 0.05 – 0.20, Fe2O3 0.2, Na2O 0.3 – 0.6, P2O5 £ 0.1, Dmcal = 2 – 5; pycnometric density 3.5 – 3.7 g/cm3, dust phase (mineral) composition is mainly g-Al2O3 corundum a-Al2O3, boehmite AlOOH, and a small amount of hydrargillite Al(OH)3. The high purity indices and fineness of alumina dust makes it possible to consider it a valuable technogenic raw material, suitable for producing a broad range of refractory and ceramic materials: high-alumina chamotte [36], fuzed and sintered corundum, spinels [37], mullite, codierite, anorthite, etc. This product is of considerable practical interest as a high quality raw material for producing proppant sands, high-alumina cement, aluminosilicate fiber, synthetic mica, catalyst carriers and abrasives. It should be noted especially

High-Alumina Technogenic Raw Material

that use of this fine alumina dust makes it possible to prepare high-strength corundum ceramic (ultimate strength in compression up to 300 MPa), and spinel-periclase clinker (ultimate strength in compression up to 260 MPa) [36, 37] without additional raw material grinding. CONCLUSION According to a collection of scale criteria (volume of current production and presence in dumps), substance and grain size composition, technological efficiency and semifunctional use, five main sources have been revealed for technogenic high-alumina mineral raw materials: ferroalloy aluminothermal slag, organic synthesis catalyst waste, abrasive enterprise slurry, secondary aluminum slag, and dust from alumina production furnaces. On the basis of a detailed study of chemical, mineral and grain size composition, physicochemical properties, and performance with heat treatment (up to melting), for technogenic raw material, manufacturing schemes have been developed for more than twenty forms of refractory products. With comprehensive waste-free use of recycling of high-alumina technogenic raw materials it is possible in addition to prepare not only refractories, but also a number of other valuable products: metals, ferroalloys, abrasives, ceramics, sitalls, glass, pigments, binders, heat insulation and other materials. REFERENCES 1. V. A. Perepelitsyn, N. F. lebedev, L. B. Khoroshavin, et al., “Technogenic raw material for refractory production,” Tekhnogen-98. Second Sci.-Tech. Conf on Processing technogenic Formations, Ural Inst. of metals, Ekaterinburg (1998). 2. V. A. Perepelitsyn, Technogenic Raw Materials of the Urals. “Refractories-91, Technology and Application,” Proc. All-Union Sci.-Tech. Conf, Western Inst. of Refractories, Chelyabinsk (1991). 3. V. A. Perepelitsyn, V. M. Rytvin, I. V. Kormina, et al., “Composition and properties of the main types of aluminothermic slag at the Klyuchi Ferroalloy Works,” Refractories and Industrial Ceramics, 47, No. 5, 264 – 268 (2006). 4. V. A. Perepelitsyn, V. M. Rytvin, and V. G. Ignatenko, “Technogenic treasure of the Urals,” Mineralnoe Syr’e Urala, No. 4, 24 – 34 (2007). 5. L. I. Leont’ev, V. M. Rytvin, S. I. Gil’varg, et al., “Combined treatment of ferroalloy. Aluminothermal slag,” Stal’, No. 4, 72 – 75 (2009). 6. V. A. Perepelitsyn, Bases of Technical Mineralogy and Petrography [in Russian], Nedra, Moscow (1987). 7. D. S belyanki, V. V. Bogolyubov, and V. V. lapin, “Lower oxides of titanium in slags of aluminothermal process,” Dokl. Akad. Nauk SSSR, LXV, No. 5, 685 – 688 (1949). 8. A. Pirogov, E. N. Leve, and P. D. Dyatikop, “Use of high-alumina slags as expanding fillers,” Proc. Ukr. NIIO, No. 5 (LII), 257 – 265 (1960).

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9. V. M. Bezhaev, V. A. Perepelitsyn, and Yu. I. Savchenko, Features of Titanium-Alumina Slag Solidification [in Russian], UrO AN SSSR, Ekaterinberg (1988). 10. V. A. Perepelitsyn, I. V. Yukseeva, and L. V. Ostryakov, “High quality refractrory raw material,” Mineralnoe Syr’e Urala, No. 3, 14 – 31 (2006). 11. A. N. Abyzov, V. A. Perepelytsyn, V. M. Rytvin, et al., “Heat-resistant concrete based on aluminothermic slags of the Klyuchevskii Ferroalloys Plant,” Refractories and Industrial Ceramics, 48, No. 6, 397 – 400 (2007). 12. A. S. Berezhnoi, “Physical chemistry of spinelids and their use in refractory material technology,” Proc. devoted to 60 years of P. P. Budnikov, Metallurgizdat (1946). 13. F. Z. Dolkart, “Use of titanium-alumina slag for refractory manufacture,” Ogneupory, No. 7, 300 – 305 (1956). 14. V. A. Bron, M. I. Diesperova, and G. S. Kotova, “Effect of additions, fineness ands firing temperature on sintering of caustic dust,” Ogneupory, No. 5, 221 – 226 (1964) 15. V. A. Rovnushkin, S. A. Spirin, V. V. Kromm, et al., “Use of slags of aluminothermal ferroalloy and master alloy production for extra-furnace treatment of steel,” Élektrometalluriya, No. 4, 10 – 12 (2009). 16. A. V. Gorokh and L. N. Rusakov, Petrographic Analysis of Processes in Metallurgy [in Russian], metallurgiya, Moscow (1973). 17. A. Perepelitsyn, V. M. Rytvin, S. I. Gil’varg, et al., “Self-disintegrating ferrochrome aluminothermal slag — semifunctional technogenic raw material,” Refractories and Industrial Ceramics, 50, No. 5, 328 – 332 (2009). 18. V. A. Bron, I. A. Savkevich, and R. S. Mil’shenko, “High-alumina refractories from chromium metal production slag,” Ogneupory, No. 2, 49 – 55 (1957) 19. A. A. Shaposhnikova, Kh. M. Papakin, T. S. Ignateva, et al., “production and testing of ladle brick with addition of chromium-alumina slag,” Ogneupory, No. 1, 3 – 7 (1961). 20. V. A. Bron and K. P. Semacina, “Chromium-alumina concretes and block objects,” Ogneupory, No. 9, 385 – 388 (1953). 21. D. Yuzvuk, V. V. Saparov, and A. D. Khomutina, “Ladle brick with chromium-alumina slag,” Ogneupory, No. 9, 388 – 391 (1962). 22. V. A. Perepelitsyn, V. M. Rytvin, S. I. Gil’varg, et al., “Aluminophobic refractory materials,” Ogneupory Tekhn. Keram., No. 11, 11 – 16 (2007). 23. . A. Perepelitsyn, V. I. Sizov, V. M. Rytvin, et al., “Wear-resistant refractories in aluminum pyrometallurgy,” Refractories and Industrial Ceramics, 48, No. 4, 242 – 245 (2007). 24. V. A. Perepelitsyn, V. A. Proshkin, V. M. Rytvin, et al., “Non-traditional domestic refractory materials for aluminum metallurgy,” Refractories and Industrial Ceramics, 49, No. 4, 257 – 260 (2008). 25. É. V. Degtyareva, Ya. Z. Shapiro, N. V. Gul’ko, et al., “Technology of spinelid objects using chemical production waste as raw material,” Ogneupory, No. 2, 36 – 44 (1974). 26. É. V. Degtyareva, I. I. Kabakova, G. R. Kotel’nikov, et al., “High-alumina objects from chemical production waste,” Ogneupory, No. 4, 39 – 43 (1976). 27. É. V. Degtyareva, I. I. Kabakova, M. V. Koetskii, et al., “Production of high-alumina objects and mixes using chromium-containing waste,” Ogneupory, No. 8, 8 – 10 (1976). 28. K. T. Vil’danova, R. R. Bairashev, E. V. Svezdina, et al., “Petrochemical and oil processing waste in heat-resistant materials,” Prco. All-Union Sci.-Tech. Meeting “Secondary resources – economic reserves and improvement of the environment,” VSNTO, Sumy (1987).

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29. S. I. Sergeev, “Heat-resistant concretes based on aluminochromium binder and industrial waste,” Proc. materials and Construction for Assembled Building of Heating Units,” UralNIIstromproekt, Chelyabinsk (1982). 30. A. K. Purgin, N. S. Sterengarts, G. V. Orlov, et al., “Quartz-corundum refractory concretes,” Ogneupory, No. 2, 35 – 38 (1983). 31. U. Sh. Shayakhmetov, Phosphate Composite Materials and Experience of Their Application [in Russian], RITs Staraya Ufa (2001). 32. B. A. Fomin, V. I. Moskvitin, and S. V. Markov, Metallurgy of Secondary Aluminum [in Russian], Intermet Inzhiniring, Moscow (2004). 33. T. V. Bayandina, “Technology of spinel-periclase material and periclase-spinel refractories using secondary aluminum produc-

V. A. Perepelitsyn et al.

tion waste,” Author’s Abstr. Diss. Cand. Tech. Sci., Moscow (2009). 34. S. Yu. Pliner and S. F. Smot’ev, RF Patent 2163227, Method for manufacturing ceramic objects from aluminum slags, Claim 07.1.00, Publ. 02.20.01, Byul. No. 7. 35. V. M. Rytvin and S. V. Kuz’min, “Production of ferrosilicoaluminum from dump slags of secondary aluminum and its alloys processing,” in: Ecological Problems of Industrial Regions [in Russian], Ural-Print UIM, Ekaterinburg (2001). 36. V. A. Kamenskikh, V. Ya. Davydov, K. G. Zemlyanoi, Et al., “Preparation of high-alumina chamotte based on electric filter dust from alumina calcining furnaces,” Proc. Internat. Congr. 300 Years of Metallurgy, URGU, Ekaterinburg (2001). 37. I. D. Kashcheev, V. A. Kamenskii, K. G. Zemlyanoi, et. al., “Synthesis of spinel from caustic magnesite and alumina production dust,” Ogneupory, No. 8, 17 – 20 (2003).