High Magnesia Research Articles

Synthesis of Magnesia–Hercynite-Based Refractories from Mill Scale and Secondary Aluminum Dross: Implication for Recycling Metallurgical Wastes

This study investigates the synthesis of magnesia–hercynite-based refractories using blends of magnesia powder, aluminum dross (AD), mill scale (MS), and graphite, focusing on the effects of carbon concentration and heating temperature. The results demonstrate successful synthesis at 1550 °C and 1650 °C, with high magnesia content (C80 and D80) leading to the formation of distinct phases, including MgO, FeAl2O4, MgFeAlO4, CaMg(SiO4), and Ca3Mg(SiO4)2, which influence the ceramic’s microstructure and mechanical properties. Increased magnesia content reduces porosity and enhances crushing strength, while heating to 1650 °C significantly improves densification and nearly doubles cold crushing strength, from 43.77–58.97 MPa at 1550 °C to 76.79–95.67 MPa at 1650 °C. These findings suggest that the synthesized refractories exhibit properties comparable to commercial magnesia–hercynite bricks, with potential for the further development for industrial rotary kiln applications.

Early Islamic glass (7th- 10th centuries AD) in Unguja Ukuu, Zanzibar: A microcosm of a globalised industry in the early 'Abbasid period.

Eighty-two glass vessels, recovered from the excavations at the ancient Swahili settlement and port of Unguja Ukuu in Zanzibar, Eastern Africa, were analysed using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). The results show that all of the glass samples are soda-lime-silica glass. Fifteen glass vessels belong to the natron glass type and are characterised by low MgO and K2O (<1.50%), suggesting they were made from natron, a mineral flux that was widely used during the Roman period and Late Antiquity. Sixty-seven glass vessels belong to the plant ash glass type, characterised by high magnesia and potash levels (>1.50%), suggesting plant ash was the main alkali flux. Based on the major, minor and trace elements, three different compositional groups were identified for the natron glass and three were identified for the plant ash glass: (1) UU Natron Type 1, (2) UU Natron Type 2, (3) UU Natron Type 3, (4) UU Plant ash Type 1, (5) UU Plant ash Type 2 and (6) UU Plan ash Type 3. Comparison with contemporary Middle Eastern glass groups shows that UU Natron Types 1, 2 and 3 correspond to Egypt II high Na2O, Levantine I and Levantine II respectively, while UU Plant ash Type 1 matches closely with Samarra Group 2. UU Plant ash Types 2 and 3 have unique chemical fingerprints that do not match any of the contemporary plant ash glass groups, but their chemical compositions show some affinity with the old Sassanian plant ash glass, suggesting a possible Mesopotamian provenance. Combined with existing research on early Islamic glass, the authors reveal a complex trading network in the globalisation of Islamic glass, particularly involving glass corresponding to modern Iraq and Syria, in the 7th- 9th centuries AD.

The dating and provenance of glass fragments from the site of Serabit el-Khâdim, Sinai

Serabit el-Khâdim, located on the western coast of the Sinai Peninsula, is the site of an ancient turquoise mine established in the early 12th Dynasty (c. 1985 BCE) and active between the 18th and 20th Dynasties (c. 1550–1136 BCE). The temple dedicated to Hathor at Serabit detail the number of offerings made, thereby recording the level of activity at Serabit during each reign. The last offerings were made by Rameses VI (1143–1136 BCE) corresponding with the collapse of the Late Bronze Age before the site was abandoned. 976 glass fragments were given to the Ashmolean Museum by Flinders Petrie following his 1905–6 excavations. 41 fragments from the collection were selected for LA-ICP-MS analysis with the aim of provenancing and dating an unknown collection of glass using composition and available stylistic features to further narrow the date of manufacture and therefore indicate the possible workshop of origin. The analysis showed that all 41 fragments are of Egyptian provenance and of standard Late Bronze Age high magnesia plant ash glass, except one fragment which is a unique example of natron blue glass applied as decoration to a white plant ash vessel body. Subtle compositional differences show that 18th Dynasty plant ash glass, plant ash Ramesside glass and natron Ramesside glass are all present, therefore corresponding with the known Egyptian activity at Serabit.

Fundamental Study on the Re-utilization of Waste Magnesia-Carbon Bricks as MgO Additive for Iron Ore Sintering

Waste magnesia-carbon bricks (MCB) exhibit great potential for being reutilized as MgO additive for iron ore sintering due to their main composition of high activity magnesia and extra carbon content. In this paper, the combustion characteristics of the carbon component of waste MCB were first studied by thermogravimetric, derivative thermogravimetric and differential scanning calorimetry thermal analysis. The influence of waste MCB utilization as MgO additive on the mineralization of sinter raw materials was also systematically investigated. The main conclusions are shown as below: (1) Compared with anthracite, the carbon component of waste MCB has relatively worse flammability and combustibility, and its combustion heat per unit mass is less; (2) As the MgO content of sinter increases from 2.0 to 3.0 wt%, the advantage of using waste MCB, compared with dolomite, as MgO additive in the crystallinity degree of sinter gradually appears; (3) At the MgO content of 3.0 wt%, the sinter using the combination of waste MCB and dolomite as MgO additive has higher content of calcium ferrite, and the distributions of main mineral compositions and pores are more uniform than the sinter totally using dolomite or waste MCB as MgO additive.

Efficiency Estimation of the Bacal Siderites Using to Increase Stability of Steel-Melting Agregates Lining

&#x0D; &#x0D; &#x0D; During the melting processes in steel-melting aggregates, lining destruction takes place due to the Magnesium oxide of lining dissolution in slag. In this study, different materials containing Magnesium oxide have been introduced into slag to increase lining stability. Efficiency estimation of raw siderite (10-0 mm class) using for this aim is considered in the present work. Initial slag (basic capacity СаО/SiO2=2,1) of industrial ASM (Arc Steel Melting) was corrected by high magnesia introduction additives (siderite). Slag has been loaded into a magnesia crucible, heated up to 1700∘C, aged during 1 hour and cooled with the furnace. The final slag phase composition analysis detected considerable changes in it: increase of MeO-phase refractory with MgO prevalence (melting temperature 2800 ∘С) and replacement of monocellitic silicate component (CaO⋅MgO⋅SiO2, melting temperature 1498 ∘С) by larnite (β-2CaO ⋅SiO2 melting temperature 2130 ∘С). Crucible slag resistance was estimated by thinning of it walls. Experiment results confirmed affect of MgO content in slag to linings solubility in it. It was determined that siderite additives increase MeO-phase (melting temperature more than 2000 ∘С) content in slag approximately by 30 % that is rather essential for lining service period increasing. It is confirmed that siderite additives prolongate magnesia lining stability of steel-making aggregates.&#x0D; &#x0D; &#x0D; &#x0D; Keywords: Bacal siderite, refractory lining, steel-making aggregates, crucible, monocellit, magnesia&#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D;

Effect of Magnesia Addition in Stability of Cobalt Catalysts Supported on Alumina for Hydrogen Generation by Glycerol Steam Reforming

Cobalt catalysts were prepared by wet impregnation of four distinct supports: alumina, magnesia and two mixed supports of alumina with magnesia (10 and 30 wt%), prepared by wet impregnation of magnesia precursor on alumina. Magnesia addition decreased catalyst acidity and reduced spinel phase formation; however, high magnesia content (30 wt%) decreased catalyst reducibility and cobalt dispersion. The catalysts were evaluated on steam reforming of glycerol for 30 h at 500 °C, GHSV of 200,000 h−1 and a glycerol solution 20% v/v in the feed. All catalysts, except the catalyst supported on pure magnesia, presented deactivation during reaction time, because of coke formation and reoxidation of metallic cobalt phase, mainly for the catalyst supported on 30%MgO–Al2O3. The catalyst supported on Al2O3 exhibited the highest mean conversion to gas (42.4%) and hydrogen yield (31.2%) during time on stream. However, the catalyst supported on 10%MgO–Al2O3 presented higher stability in terms of glycerol conversion to gas and hydrogen yield, associated with preferential formation of filamentous coke instead of amorphous coke.

A New Technique to Quantitatively Determine the Periclase Content in High Magnesia Portland Cement

An accurate quantification of periclase in high magnesia Portland cement (HMPC) is vital to evaluate the expansive property of this cement at a later age in practice. However, the existing methods to achieve this quantification are either limited in number or produce inaccurate results. In this study, a new Technique to quantitatively determine the content of periclase in HMPC was demonstrated by combining an autoclave test, a thermogravimetric analysis (TGA), and a chemical analysis; this was achieved by using the periclase standard substance (PSS) as the internal standard. The accuracy of this Technique was evaluated with regard to the recovery rate. Herein, an analytical grade reagent such as magnesium carbonate basic (Mg(OH)2·3MgCO3·3H2O) or magnesium hydroxide (Mg(OH)2) calcined at 1400 ℃ is recommended to be the PSS. The autoclave pressure should be 2.2 MPa, and the autoclave time should be 4 h. This novel Technique can avoid the interference of fused MgO in cement, and eliminate the influence of Mg(OH)2 and Ca(OH)2 (induced by the partial overlapping of their decomposition temperatures during TGA) on the periclase content. The results show that the recovery of PSS is between 99.92% and 100.14%, indicating that the Technique presents a good recovery effect and a relatively high accuracy. Therefore, this new Technique can be used to evaluate the expansive properties of HMPC and serve as a guidance for using HMPC in different practical applications according to the demand of a project.

Hydration characteristics and microstructure of magnesium phosphate cement in presence of Cu2+

Heavy metal pollution is one of the severe problems facing the environment, and magnesium phosphate cement (MKPC) is increasingly used for the solidification/stabilization (S/S) treatment of heavy metals due to their excellent properties, the hydration characteristics and microstructure of MKPCs plays a key role in the S/S treatment of heavy metals, but this has not been sufficiently studied. In this study, the effects of Cu2+ on the hydration characteristics of MKPCs were analyzed using compressive strength, setting time, pH, heat of hydration, the phases and microstructure of samples were investigated by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy measurements and Cu2+ leaching rate of samples were also measured. The results indicated that the addition of Cu2+ reduced the compressive strength of MKPCs and also delayed the setting time at high magnesia to potassium dihydrogen phosphate (M/P) ratios. When the addition of Cu2+ was 4%, the compressive strength of the sample cured 12 h decreased by 73% and the final setting time of the sample was prolonged by 94% with the M/P ratio of 4:1. Cu2+ did not affect the main hydration products of MKPCs, but lowered the change rate of the pH, got the smaller exothermic hydration peak, and reduced crystallinity of the main hydration product. Moreover, the leaching concentration (1.7 mg/L) of Cu2+ measured using the toxicity characteristics leaching procedure was lower than the TCLP (Toxicity Characteristic Leaching Procedure) requirement (15 mg/L). A lower M/P ratio is beneficial to improve the S/S performance of Cu-incorporated MPC.

The wet high intensity magnetic separation of magnesite ore waste

The wet high intensity magnetic separation of magnesite ore waste stocked in an open pit of a magnesite mine was investigated in this paper. The received sample was subjected to physical, chemical, thermal and phase characterizations. The magnesite ore waste sample contained 77.69 % MgCO3 and a considerable amount of Fe2O3 (3.14 %). The unwanted silica and iron impurities were removed and a high-grade magnesite was experimentally obtained. Results have shown that a high-grade magnesite was obtained after subjecting the non-magnetic portion of the processed sample twice at 1.8 T. It was possible to increase the magnesite content up to 91.03 % while reducing the iron content to 0.32 % by using magnetic separation. After the calcination process at 1000?C, the sample showed mass loss on ignition of 52 % and contained 85.39 % MgO with 0.32 % Fe2O3. The final product can be used in chemical and metallurgical applications where high magnesia contents are required. The experimental results provide useful information on wet magnetic separation of magnesite wastes.

Изучение возможности переработки отходов обогащения магнезита с получением высокоактивной магнезии

Изучение возможности переработки отходов обогащения магнезита с получением высокоактивной магнезии

Stabilization of Ladle-Treatment Slags in Steel Production

Ladle-treatment slags are primary wastes from steel production. Slag utilization is prevented by its spontaneous decomposition as a result of polymorphic transformation of dicalcium silicate with decrease in slag temperature. At OOO NLMK-Kaluga, the slag is stabilized by the introduction of boron oxide in the high–magnesia flux during ladle treatment. Industrial tests indicate stabilization of the slag and the formation of a protective layer on the lining, preventing slag corrosion.

뉴칼레도니아산 니켈라테라이트광의 분급 연구

Nickel laterite ore is classified into two principal ore types: saprolite (silicate ore) and limonite (oxide ore). Saprolite-type ore characterized by high magnesia and silica contents is treated by pyrometallurgy process. On the other hand, limonite-type ore is subjected to hydrometallurgy process to produce nickel products. Hydrometallurgy process requires that a raw material to meet the demands that Si+Mg contents lower than 10% and Fe content over than 40%. It is therefore required that separation of saprilite-type ore to use nickel laterite ore as a raw material for hydrometallurgy process. In this study, separation of sparolite-type ore and limonite-type ore from nickel laterite ore from New Caledonia has been tried by dry classification. The results show that -5 mm size fraction and +5 mm size fraction of the nickel laterite ore contains mainly limonite-type ore and saprolite-type ore, respectively. To understand the moisture content of the raw ore on the dry classification, nickel laterite ore with different moisture contents of 23.0% and 9.1% were subjected to the dry classification. The results show that drying of the ore makes the separation more efficient as the amount of the fine product, that can be subjected to hydrometallurgy process without further separation or drying operations, was increased.

Influence of magnesia in the infiltration of magnesia-spinel refractory bricks by different clinkers

In cement production, which involves the production of cement clinker in rotary kilns, the main refractories used are magnesia-spinel bricks. These bricks may suffer infiltration by the clinker liquid phase, resulting in the corrosion of the spinel and the formation of low refractoriness mineralogical phases, such as the Q phase (C 20 A 13 M 3 S 3 ), which compromises refractory performance. Thus, the aim of this work is to correlate the infiltration resistance of magnesia-spinel bricks made from different grades of magnesia by clinker collected in three different cement plants (A, B and C). The purity of magnesia, besides its physical properties, strongly influences the proper ties and the infiltration resistance of magnesia-spinel bricks; as such the use of high grade magnesia is essential for producing high performance refractories.

Precipitação química de estruvita: Recuperação de nutrientes em reator cônico de leito fluidizado utilizando magnésia industrial de baixo custo

O processo físico-químico da precipitação de estruvita é uma técnica que apresenta elevado potencial na remoção de nutrientes, a partir de diferentes tipologias de efluentes. O presente estudo teve por objetivo a avaliação de um composto industrial com elevado teor de magnésia e baixo custo como fonte reagente alternativa de magnésio e alcalinidade necessários ao processo de precipitação, tornando-o economicamente viável com a redução de gastos despendidos com químicos. Suspensões de Mg(OH)2 foram obtidas e tiveram desempenho avaliado em função da remoção de nutrientes, a partir de um efluente sintético rico em N-NH4+ e P-PO43-, e qualidade dos cristais gerados, com a identificação do mineral de interesse - estruvita. O experimento foi realizado em escala laboratorial utilizando reator cônico de leito fluidizado operado em semi-contínuo. O adequado controle operacional do pH (8,0-8,5) pela adição automatizada da suspensão de Mg(OH)2 possibilitou uma considerável remoção de P-PO43-, que atingiu valor médio igual a 93,5%. Os sólidos recuperados no processo apresentaram pureza de, aproximadamente, 84% de estruvita.

Glass Beads from 15th-17th CenturyCEJar Burial Sites in Cambodia's Cardamom Mountains

A total of 74 glass beads, included as grave goods in 15th–17th century CE jar burials from Cambodia's Cardamom Mountains, were analysed using laser ablation – inductively coupled plasma – mass spectrometry (LA–ICP–MS). Several glass types were identified, including two subtypes of high-alumina mineral soda glass, and lead–potash glass. The final glass type represents a newly discovered and previously unidentified type of high-alumina soda glass, with high magnesia (m-Na–Al Mg>). This study represents the first glass data from the mid-second millennium CE from Cambodia and sheds light on the multiple long-distance maritime exchange networks in which the upland people buried in the jars were participating.

Composition and technology of 18th century high magnesia faïences from Fulda

In 1996, archaeological excavations close to the ancient Fulda faïence manufacture site unearthed a rich deposit of faïence wastes (biscuits, faïences, technical ceramics). The manufacture was founded in 1741 by Prince Abbot Amand von Buseck and closed down in 1761. This first archaeometric study of a German faïence manufacture included 31 samples produced between 1742 and 1760. Analytical techniques were optical microscopy, X-ray fluorescence, X-ray diffraction and scanning electron microscopy, coupled to an energy-dispersive X-ray spectrometer. Biscuits and faïences are MgO- (5–13wt.%) and CaO-rich (9–20wt.%), easily distinguishable from the two French Mg-rich productions of Granges-le-Bourg and Lunéville that we know today. Three samples show high P2O5 (2.6–3.3wt.%). Such unusual concentrations are not due to the admixing of crushed bones to the clay during processing, or to one of the well-known post-firing secondary contamination processes, but are caused by the presence of sharp edged, rhomboedric grains with sizes around 20–30μm and an overall chemical composition of apatite. These fragments are interpreted to be remnants of primary phosphoritic elements, present ab initium in the clay, and give some hints as to the origin of the raw materials used. Phosphoritic layers can be found in the German Trias, mostly in dolomitic marls of the Middle Keuper. Such marls form the basement on which Fulda is built and could easily have been extracted by the Fulda manufacture. The high MgO values of the faïences can therefore be linked to the presence of dolomitic grains in the plastic raw material, corroborated by the positive MgO/CaO correlation. Firing temperatures of the faïences were, according to their XRD patterns, mostly between 950 and 1050°C.

Progress of High Purity Magnesium Oxide Preparation

The research status of high purity magnesium oxide preparation is introduced in this paper. First, process for preparing high purity MgO is summarized, the global and domestic production status of high purity magnesia is also described. Finally, the problems and disadvantages of current MgO preparation methods are concluded, also development direction of preparation method basing on brine utilization in the production of MgO is put forward.

Synthesis, characterization and catalytic performance of binary CeO2–MgO oxides in the dehydrogenation of ethylbenzene

Binary CeO2–MgO oxides with various Ce/Mg mol ratios were prepared by the co-precipitation method and were tested in the dehydrogenation of ethylbenzene to styrene. The obtained materials were characterized by N2 adsorption, X-ray diffraction, and X-ray photoelectron spectroscopy. The N2 adsorption showed that CeO2–MgO oxides were mesoporous materials and the BET surface area increased with increasing magnesia content. The fluorite type structure of ceria was observed in samples with low magnesia content while the mixture of the ceria phase and the magnesia phase existed simultaneously in samples with high magnesia content. The results showed that the Ce4+–Mg2+–O2− couple in CeO2/MgO catalyst could be supposed to be an active site in the dehydrogenation of ethylbenzene.

The Reaction Mechanism between Aluminum-Magnesia-Spinel Composite Material and RH Slag

Unfired specimens were made with different aluninum content (0,2%,4%,6%,8%) respectively ,using high pure magnesia , magnesia-spinel and Aluninum as the main raw material. Unfired specimens were treated under the condition:110°C×24h drying,then 300°C×6h heating treatment.The properties and microstructure of the specimens were analyzed to investigate the reaction mechanism of these speciments and RH refinery slag.The result are shown that the addition of aluninum improves cold crushing strength of specimens,reaching to 63Mpa. The specimen with aluninum content of 8% shown the best slag resistance. The reaction mechanism between aluninum-magnesia-spinel complosite material and RH slag is different from magnesite-chrome brick. The major penetration element is Ca, and the Ca elment penetrated into the matrix reacts with corundum turning out a CA2 protective layer which can stop penetrating of slag.

ANALYSIS OF LATE BRONZE AGE GLASS AXES FROM NIPPUR—A NEW COBALT COLOURANT

A multidisciplinary study of a unique group of Late Bronze Age (LBA) ceremonial glass axe heads and other artefacts shows that these are the first significant group of glasses coloured with cobalt to be identified from the Near East. The axes were excavated from the site of Nippur, in present‐day Iraq. Several are incised with the names of three kings, which dates the material to the 14th–13th centuries bc. Analysis by laser ablation inductively coupled plasma mass spectrometry (LA–ICPMS) indicates that the glass had high magnesia (MgO) and potash (K2O) associated with a plant‐ash flux and was coloured blue by copper or a combination of copper and cobalt. These glasses are similar, but not identical, in major element composition to blue‐coloured glasses manufactured in ancient Egypt and elsewhere in Mesopotamia in the same period. However, the Nippur cobalt‐ and copper‐coloured glasses exhibit significantly different trace elemental compositions compared to Egyptian glass coloured with cobalt, showing that the ancient Near Eastern glassmakers had clearly identified and utilized a distinctive cobalt ore source for the colouring of this glass. Since it was previously thought that the only cobalt ores exploited in the LBA were exclusively of Egyptian origin, this new finding provides new insights on the origins of glass and how it was traded during the Bronze Age period.