Dry processing technology of exhaust gas emitted by roasting of rare earth concentrates with concentrated sulfuric acid

The aim of this paper is to explore material flow analysis, study the resource consumption and environmental impact of the production preparation process of typical rare earth materials. The results showed that in the beneficiation processes, producing one ton of rare earth concentrates (Rare Earth Oxide, REO50%) will also produces 27 tons of iron ore and 21 tons of tailings. The recovery of rare earths is only 16.8%. In roasting processes, roasting one ton (REO50%) of rare earth concentrates will emits 150 ~ 200Kg sulfuric acid mist, 500 ~ 600Kg sulfur dioxide, 30 ~ 40Kg fluoride, 30 ~ 50Kg smoke and1t (containing thorium) radioactive slag, and 1.2 tons of concentrated sulfuric acid should be used. The lower recoveries and large-scale of concentrated sulfuric acid used in roasting processes in rare earth industry are the main reasons lead to high pollution and high emissions.

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Complex Rare Earth Minerals Sulfate Decomposition Techniques Investigation

Materials Science Forum ◽

10.4028/www.scientific.net/msf.946.580 ◽

2019 ◽

Vol 946 ◽

pp. 580-584

Author(s):

K.D. Naumov ◽

K.A. Karimov ◽

A.M. Klyushnikov

Keyword(s):

Rare Earth ◽

Sulfuric Acid ◽

Atmospheric Pressure ◽

Pressure Leaching ◽

Decomposition Techniques ◽

The Third ◽

Iron Aluminum ◽

Rare Earth Minerals ◽

Concentrated Sulfuric Acid ◽

Major Factors

This article presents a study of Tomtor rare earth ore decomposition. This material contains a lot of valuable components such as REE and niobium (mas., %: 12,8 ΣREO (rare earth oxides), 0.039 Sc, 18.4 P2O5, 9.9 Fe, 9.0 Al, 0.24 ThO2, 8.2 Nb2O5). The study aims to find efficient ways of processing this deposit. Technologies using the sulfuric acid as the main reagent to leach are described in this article. Investigation has three trends. The first trend is agitation leaching at low sulfuric acid concentrations, temperatures up to 95 °C and atmospheric pressure. The second trend is pressure leaching at low sulfuric acid concentrations, high temperatures (up to 180 °C) and high pressure. The third trend is high temperature sulfatization with concentrated sulfuric acid at elevated temperature (up to 180 °C) and atmospheric pressure followed by aqueous leaching. The dependence of target components (rare earth elements, scandium, phosphorus) and the impurity (iron, aluminum, thorium) extractions into solution from major factors was studied.

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Gallium Arsenide Integrated Circuits Decapsulation Technique Using Mixed Acid Chemistry For Die-Level Failure Analysis

10.31399/asm.cp.istfa2018p0496 ◽

2018 ◽

Author(s):

Harold Jeffrey M. Consigo ◽

Ricardo S. Calanog ◽

Melissa O. Caseria

Keyword(s):

Gallium Arsenide ◽

Sulfuric Acid ◽

Nitric Acid ◽

Integrated Circuits ◽

Failure Analysis ◽

Mixed Acid ◽

Optimum Parameters ◽

Plastic Package ◽

Fuming Nitric Acid ◽

Concentrated Sulfuric Acid

Abstract Gallium Arsenide (GaAs) integrated circuits have become popular these days with superior speed/power products that permit the development of systems that otherwise would have made it impossible or impractical to construct using silicon semiconductors. However, failure analysis remains to be very challenging as GaAs material is easily dissolved when it is reacted with fuming nitric acid used during standard decapsulation process. By utilizing enhanced chemical decapsulation technique with mixture of fuming nitric acid and concentrated sulfuric acid at a low temperature backed with statistical analysis, successful plastic package decapsulation happens to be reproducible mainly for die level failure analysis purposes. The paper aims to develop a chemical decapsulation process with optimum parameters needed to successfully decapsulate plastic molded GaAs integrated circuits for die level failure analysis.

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PRODUCTION OF SULFOCATIONITE BY MODIFICATION OF NATURAL COAL WITH CONCENTRATED SULFURIC ACID

SERIES CHEMISTRY AND TECHNOLOGY ◽

10.32014/2020.2518-1491.50 ◽

2020 ◽

Vol 3 (441) ◽

pp. 104-109

Author(s):

N.A. Bektenov ◽

◽

N.C. Murzakassymova ◽

M.A. Gavrilenko ◽

А.N. Nurlybayeva ◽

...

Keyword(s):

Sulfuric Acid ◽

Concentrated Sulfuric Acid ◽

Natural Coal

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Addition of primary alcohols to 3-chlorononafluoro-1,5-hexadiene and perfluoro-1,3,5-hexatriene

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19851714 ◽

1985 ◽

Vol 50 (8) ◽

pp. 1714-1726 ◽

Cited By ~ 3

Author(s):

Václav Dědek ◽

Igor Linhart ◽

Milan Kováč

Keyword(s):

Sulfuric Acid ◽

Primary Alcohols ◽

Principal Product ◽

Allyl Rearrangement ◽

Concentrated Sulfuric Acid ◽

Sodium Alkoxide

Sodium alkoxide-catalyzed addition of methanol, ethanol and propanol to 3-chlorononafluoro-1,5-hexadiene (I) proceeds at temperatures -35 °C to 8 °C with allyl rearrangement, affording 1,6-dialkoxy-1,1,2,3,4,4,5,6,6-octafluoro-2,4-hexadiene (V) as the principal product, along with 1,6-dialkoxy-1,2,3,3,4,5,6,6-octafluoro-1,5-diene (VI) and trans-1,6-dialkoxy-1,1,2,3,4,4,5,6,6-nonafluoro-2-hexene (VII). The ethers Va-Vc consist of the cis,trans- and trans,trans-isomers in about 3 : 1 ratio, whereas the ethers VIa-VIc have trans,trans-configuration. Ethers Vc and VIc react with concentrated sulfuric acid to give dipropyl 2,3,4,5-tetrafluoro-2,4-hexadienedioate (IX) and dipropyl 2,3,4,4,5-pentafluoro-2-hexenedioate (X), respectively, whereas the ether VIIc affords a mixture of propyl 6-propyloxy-2,3,4,4,5,6-heptafluoro-2-hexenoate (XI) and ester X. Addition of methanol to perfluoro-1,3,5-hexatriene (II) affords 1,1,2,3,4,5,6,6-octafluoro-1,6-dimethoxy-3-hexene (XIII) as the principal product.

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ChemInform Abstract: ADAMANTANE AND ITS DERIVATIVES PART 30, ON REACTIONS OF 2-METHYL-ADAMANTANE IN CONCENTRATED SULFURIC ACID

Chemischer Informationsdienst ◽

10.1002/chin.197519181 ◽

1975 ◽

Vol 6 (19) ◽

pp. no-no

Author(s):

S. LANDA ◽

J. HLAVATY

Keyword(s):

Sulfuric Acid ◽

Concentrated Sulfuric Acid

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4,5,6-Trichloropyrimidine-2-carboxamide

Molbank ◽

10.3390/m1190 ◽

2021 ◽

Vol 2021 (1) ◽

pp. M1190

Author(s):

Andreas S. Kalogirou ◽

Panayiotis A. Koutentis

Keyword(s):

Sulfuric Acid ◽

Elemental Analysis ◽

Maldi Tof ◽

Concentrated Sulfuric Acid

Reaction of 4,5,6-trichloropyrimidine-2-carbonitrile (1) with concentrated sulfuric acid at ca. 20 °C gave 4,5,6-trichloropyrimidine-2-carboxamide (5) in 91% yield. The new compound was fully characterized by IR, MALDI-TOF, NMR and elemental analysis.

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