PREPARATION OF CHROMIUM(IV) OXIDE MATERIALS

A novel process for the manufacture of materials containing chromium(IV) oxide from precursor molecules that contain chromium in the formal oxidation state of +4 is described.

INTERFACIAL BONDING OXIDES FOR GLASS-CERAMIC-TO-METAL SEALS

The present invention relates to structure including an interfacial seal between a glass-ceramic component and a metal component, as well as methods for forming such structures. In particular embodiments, the interfacial seal includes a metal oxide. Such interfacial seals can be beneficial for, e.g., hermetic seals between a glass-ceramic component and a metal component. 1. A method comprising:{'sub': 2', '2', '2', '3', '2', '2', '5', '2', '3, 'providing a glass-ceramic component configured to provide a glass-ceramic composition comprising of from about 65 wt. % to about 80 wt. % of SiO; from about 8 wt. % to about 16 wt. % of LiO; from about 2 wt. % to about 8 wt. % of AlO; from about 1 wt. % to about 8 wt. % of KO; from about 1 wt. % to about 5 wt. % of PO; from about 0.5 wt. % to about 7 wt. % of BO; from 0 wt. % to about 5 wt. % of ZnO; and from about 0.5 wt. % to about 5 wt. % of one or more metal oxidants;'}providing a metal component, wherein the glass-ceramic component is contacted with a portion of the metal component;{'sub': '1', 'heating the glass-ceramic component and metal component to a first temperature Tof from about 900° C. to about 1050° C.;'}{'sub': '2', 'initially cooling to a second temperature Tof from about 400° C. to about 750° C.; and'}{'sub': '4', 'further cooling the mixture to a fourth temperature Tof from about 10° C. to about 500° C., thereby forming an interfacial seal between the glass-ceramic component and the metal component.'}2. The method of claim 1 , wherein the heating step comprises rapidly cooling at a rate rgreater than about 30° C./minute to a second temperature Tof from about 400° C. to about 750° C. claim 1 , thereby minimizing formation of a cristobalite SiOphase within the glass-ceramic composition.3. The method of claim 1 , further comprising claim 1 , after the initially cooling step:{'sub': 3', '2, 'reheating the mixture to a third temperature Tof from about 750° C. to about 850° C., thereby facilitating formation of ...

Detoxification treatment method for extracting and recycling chromium from hexavalent chromium-containing residues

The present invention discloses a detoxification treatment method for extracting and recycling chromium from hexavalent chromium-containing residues, comprising steps as follows: 1) adding water to the hexavalent chromium-containing residues and mixing uniformly; 2) adding sodium sulfate, sodium chlorate and sulfuric acid to a solution obtained in step 1) and stirring, sufficiently to obtain a mixed liquid; 3) treating the mixed liquid by a hydrothermal method or direct heating; 4) after the heating treatment, naturally cooling a solid-liquid mixture to room temperature for holding; 5) separating solid residues and a chromium-containing supernatant, and washing filtered residues with water and then drying; 6) precipitating the supernatant and the water used for washing the filtered residues with a precipitant CaCl2, then centrifugally washing, dewatering and drying the precipitates; and 7) recycling a chromium-containing solution for returning to a work section, or for a treatment of recycling chromium. This method may achieve full-residue utilization with simple process, low cost, quick effect, large treating capacity and complete detoxification.

一种铬酸盐制备三氧化二铬的方法

本发明涉及一种铬酸盐制备三氧化二铬的方法，是以铬酸盐为原料，用含碳还原性气体作还原剂，在125‑780℃的温度下还原，得到由三氧化二铬和碳酸盐组成的还原产物，加水溶解还原产物中的碳酸盐，过滤、洗涤、烘干后得三氧化二铬产品，溶解液再经CO 2 酸化分离回收其中的碳酸盐。本发明不仅极大简化了三氧化二铬的生产工艺，而且显著降低了三氧化二铬的生产成本，并可实现整个工艺过程废水废渣的零排放。本发明具有工艺路线短，加工成本低，产品质量好，高效环保等优点，适合于三氧化二铬工业化生产。

A kind of CrO of controlled dimensions2The preparation method of nano particle

本发明的一种可控制尺寸的CrO 2 纳米颗粒的制备方法，属于纳米材料合成的技术领域。首先将CrO 3 水溶液与聚乙烯醇水溶液或乙二醇水溶液混合，在密封反应釜内水热合成前驱物纳米棒状CrOOH；再将CrOOH与纳米气相SiO 2 在氧气压力条件下制得CrO 2 /SiO 2 纳米颗粒复合物，用HF除去SiO 2 得到CrO 2 纳米颗粒。本发明通过控制SiO 2 的用量，使CrO2不同程度的分散，从而较容易控制晶粒生长；工艺简单，易操作，不需要昂贵的原料和设备，成本低，利于产业化推广。

CONTINUOUS PROCEDURE FOR THE ELEMINATION OF CHROME FROM WASTE WATER AND THE VALORISATION OF RECOVERED CHROME

Method of manufacturing ferromagnetic chroomium dioxide

The method for preparing chrome oxide green using raffinate obtained by naphthoquinones is produced

本发明公开了一种利用生产萘醌所得残液制备氧化铬绿的方法，包括以下步骤：(1)Cr(VI)的还原：在生产甲基萘醌所得残液中加入一定量的还原剂将Cr(VI)转化为Cr(III)，得到混合液；(2)酸的中和：在还原完的混合液中加入含钙化合物，将混合液的pH调至一定值；(3)Cr 3+ 的沉淀：将(2)中得到的混合物过滤，滤液中加入氢氧化物或碳酸盐，将溶液pH调至一定值，过滤，滤饼洗涤后煅烧得到氧化铬绿。本发明成功去除了残液中存在的高毒性的Cr(VI)，采用含钙化合物中和了残液中存在的过量的酸，得到的硫酸钙的利用价值更高，并通过沉淀的方式去除了残液中的Cr 3+ ，解决了该残液对环境的污染问题，实现了可持续发展。通过本发明制备的铬绿纯度达到99％以上，达到了国家规定的氧化铬绿颜料标准。

Process for producing hydroxide

고분자 물질 등에 첨가하기 위하여 적절한 입자크기를 갖고 얇은 판상을 이루며 표면적이 상대적으로 큰 범위에서 미세 특성제어가 용이한 결정성 층상 혼합금속 수산화물을 빠른 속도로 제조하는 방법이 개시되어 있다. 본 발명에 따르면, 결정성 M (II) (OH) 2 (M (II) 는 +2 산화상태를 갖는 금속원소)와 결정성 M (III) (OH) 3 (M (III) 는 +3 산화상태를 갖는 금속원소) 화합물의 물 분산물에, 이들 M (II) 및 M (III) 금속원소를 포함하는 수용성 화합물류와 층간 음이온 성분을 포함하는 화합물을 첨가하고, 혼합물 용액의 pH를 조절하여 수용성 금속 성분을 점성을 띠는 젤 형태의 혼합금속 수산화물로 변환시키고, 상기 결정성 M (II) (OH) 2 , M (III) (OH) 3 와 수용성 금속 성분으로 부터 변형된 점성을 띠는 젤 형태의 금속수산화물을 포함하는 반응 혼합물로부터, 수열 반응과정을 거쳐, 결정성 층상 혼합금속 수산화물을 제조한다. 반응에 첨가되는 수용성 화합물류의 종류, 금속수산화물에 대한 수용성 금속화합물의 첨가 비율 및 방법, 층간 음이온 성분의 종류, 반응온도, 반응시간의 적절한 선택으로 생성물인 층상 혼합금속 수산화물의 입자크기를 0.2∼2μ범위, 입자형상을 규칙적인 육각 판상으로부터 불규칙적인 모양의 판상, 비표면적의 크기를 20∼90m 2 /g 범위, 두께대 직경비를 10∼50 범위에서 유연하게 제어한다. Disclosed is a method for producing a crystalline layered mixed metal hydroxide having a suitable particle size for forming a polymer material and the like and forming a thin plate and easily controlling fine characteristics in a relatively large surface area at a high speed. According to the present invention, crystalline M (II) (OH) 2 (M (II) Is a metal element with +2 oxidation state) and crystalline M (III) (OH) 3 (M (III) Is a water dispersion of a metal element) compound having a +3 oxidation state, (II) And M (III) A water-soluble compound containing a metal element and a compound containing an interlayer anion component are added, and the pH of the mixture solution is adjusted to convert the water-soluble metal component into a viscous gel-type mixed metal hydroxide, wherein the crystalline M (II) (OH) 2 , M (III) (OH) 3 And a crystalline layered mixed metal hydroxide are prepared from a reaction mixture comprising a gel hydroxide metal hydroxide modified from a water-soluble metal component by hydrothermal reaction. The particle size of the layered mixed metal hydroxide as a product is appropriately selected by the type of water-soluble compound added to the reaction, the ratio and method of adding the water-soluble metal compound to the metal hydroxide, ...

Method of producing chromium oxide

Изобретение относится к химической промышленности и может быть использовано для производства металлического хрома. Растворяют сульфат аммония в воде до получения концентрации 35-50,4% (NH)SO.Растворяют бихромат натрия в растворе сульфата аммония при температуре 90-100°С в течение 15-40 минут при постоянном перемешивании с получением бихромата аммония и сульфата натрия. Полученную реакционную массу в виде водной суспензии подвергают термообработке при температуре 235-400°С до разложения бихромата аммония. Продукты разложения бихромата аммония отмывают от растворимых в воде веществ и подвергают повторной термообработке при температуре 800-1400°С до образования окиси хрома. Обеспечивается упрощение процесса, повышение чистоты окиси хрома СrOдо 99,3% за счет уменьшения содержания примесей и увеличения крупности частиц. РОССИЙСКАЯ ФЕДЕРАЦИЯ (19) RU (11) (13) 2 687 425 C1 (51) МПК C01G 37/02 (2006.01) ФЕДЕРАЛЬНАЯ СЛУЖБА ПО ИНТЕЛЛЕКТУАЛЬНОЙ СОБСТВЕННОСТИ (12) ОПИСАНИЕ ИЗОБРЕТЕНИЯ К ПАТЕНТУ (52) СПК C01G 37/02 (2019.02) (21) (22) Заявка: 2018115855, 26.04.2018 (24) Дата начала отсчета срока действия патента: 26.04.2018 13.05.2019 Приоритет(ы): (22) Дата подачи заявки: 26.04.2018 (56) Список документов, цитированных в отчете о поиске: RU 2258039 C1, 10.08.2005. RU (45) Опубликовано: 13.05.2019 Бюл. № 14 бихромат натрия в растворе сульфата аммония при температуре 90-100°С в течение 15-40 минут при постоянном перемешивании с получением бихромата аммония и сульфата натрия. Полученную реакционную массу в виде водной R U 2 6 8 7 4 2 5 (54) СПОСОБ ПОЛУЧЕНИЯ ОКИСИ ХРОМА (57) Реферат: Изобретение относится к химической промышленности и может быть использовано для производства металлического хрома. Растворяют сульфат аммония в воде до получения концентрации 35-50,4% (NH4)2SO4.Растворяют Стр.: 1 2012131057 A, 27.01.2014. US 4235862 A, 25.11.1980. US 4067747 A, 10.01.1978. US 4296076 A, 20.10.1981. суспензии подвергают термообработке при температуре 235-400°С до разложения бихромата ...

The method that sodium chromate prepares chrome green

本发明属于化工领域，具体涉及铬酸钠制备三氧化二铬的方法。本发明所要解决的技术问题是提供一种铬酸钠制备三氧化二铬的方法，包括以下步骤：将铬酸钠加入有机酸中进行反应，反应结束后固液分离，固体洗涤、煅烧得到三氧化二铬。本发明方法将铬酸钠直接加入有机酸，具有操作简单、产品纯度高等优点。

Process for recovery of chromium from waste solution for electroplating chromium

本发明的方法属于工业废水处理技术领域，特别适用于电镀工厂镀铬废水中铬的回收。该方法主要是在镀铬槽内放置塑料网内衬，在废水中加入亚硫酸使六价铬还原成三价铬，然后再加入氨水，与三价铬反应生成含铬沉淀，直到沉淀完全，最后进行分离。分离后的净水封闭循环，重新用于漂洗。而分离后的含铬沉淀用水进行多次清洗，除去铵离子及硫酸根离子，得到铬化合物纯品，再重复用于镀铬工艺。本发明的方法简单可行地解决了镀铬废水处理中铬对环境二次污染的问题，使之能在实际中推广应用。

Preparation method of chromium oxide lithium ion battery anode material containing lithiated vulcanized polyacrylonitrile

一种含锂化硫化聚丙烯腈的铬氧化物锂离子电池正极材料的制备方法，属于锂离子电池技术领域。本发明针对传统铬氧化物正极的电极反应动力学缓慢、首次库伦效率和比容量低等问题，所述方法为：铬氧化物制备；硫化聚丙烯腈制备；锂化硫化聚丙烯腈制备；将制备的锂化硫化聚丙烯腈和铬氧化物混合，200rpm球磨1小时，得到含锂化硫化聚丙烯腈的铬氧化物正极。本发明制备的含锂化硫化聚丙烯腈的铬氧化物锂离子电池正极材料，颗粒均匀，具有显著提升首次库伦效率、可逆电比容量和导电性的优点；该含锂化硫化聚丙烯腈，可用于其它电极材料改性，有机碳骨架具有较高的导电性、补锂容量和电化学反应电压平台，可推广到其它电极材料体系。

Chromium oxide and preparation method thereof

本发明提供了一种氧化铬及其制备方法，所述方法包括：将含有催化剂的六价铬盐溶液加入反应装置中，通入保护性气体后密闭升温，达到目标温度后持续通入还原性气体发生反应，得到混合浆料；将所得混合浆料固液分离，得到的羟基氧化铬粉体进行煅烧处理，得到氧化铬。本发明采用水热还原法由六价铬盐制备氧化铬，通过对还原性气体及反应条件的调控，增强反应过程的可控性，还原率可达99.5％以上，催化剂的加入有效提高反应速率，还原产物物相均一，粒度分布较窄，所得氧化铬产品品质较高，可达到颜料级氧化铬的标准；所述方法流程短、能耗及成本低，无污染物排放，是一种清洁生产工艺，具有显著的经济效益。

METHOD FOR PRODUCING A CRYSTALLINE PIGMENT-LIKE CR TIEF 2 O TIEF 3

AVLAEGSNANDE AV KROM UR CELLVAETSKA.

CHROME OXIDE PIGMENTS WITH REDUCED CHROMIUM CONTENT (VI)

Anhydrous chromium sesquioxide - by reducing chromium (vi) cmpd in hydrogen mixed with inert gas

Anhydrous Cr2O3 is made by reducing a Cr(VI) cpd. non-thermally-decomposable below 300 degrees C e.g. CrO3, by first heating in a non-reducing atmos at 197-280 degrees C then heating in a reducing atmos of H2 optionally mixed initially with an inert gas, at 250-300 degrees C. To avoid incomplete reduction, the latter part of the reduction, is performed using H2 in the absence of inert gas. In the parent patent the reducing atmos, consists of an H2 inert gas mixture (throughout), the reduction being more complete.

Process for the conversion of chromic anhydride into chromic oxide

PROCESS FOR PREPARING FERROMAGNETIC CHROME BIOXIDE

L'invention se rapporte au génie chimique. Elle concerne un procédé selon lequel on chauffe un mélange comprenant un ou plusieurs oxydes de chrome dans lesquels le chrome a une valence moyenne autre que + 4 en présence d'eau à haute température et sous une pression pour former une masse rigide de bioxyde de chrome, et on refroidit et on sèche le bioxyde de chrome résultant, caractérisé en ce que : on chauffe le mélange dans un anneau 10 fermé à une extrémité et défini par des parois intérieure et extérieure ayant chacune un coefficient de dilatation thermique différent de celui de la masse rigide, et un refroidit le bioxyde de chrome et l'anneau de manière qu'une de ces parois se sépare de la masse rigide, formant un passage annulaire qui permet à la vapeur d'eau de s'échapper. Utilisation pour la production de CrO2 ferromagnétique. The invention relates to chemical engineering. It relates to a process according to which a mixture comprising one or more chromium oxides in which the chromium has an average valence other than + 4 is heated in the presence of water at high temperature and under pressure to form a rigid mass of chromium dioxide. , and cooling and drying the resulting chromium dioxide, characterized in that: heating the mixture in a ring 10 closed at one end and defined by inner and outer walls each having a coefficient of thermal expansion different from that of the rigid mass, and a cools the chromium dioxide and the ring so that one of these walls separates from the rigid mass, forming an annular passage which allows water vapor to escape. Use for the production of ferromagnetic CrO2.

Method of producing ferromagnetic chromium dioxide

Изобретение относитс  к технологии получени  ферромагнитной двуокиси хрома , используемой дл  изготовлени  магнитных носителей информации. Целью изобретени  вл етс улучшение электроакустических свойств магнитных носителей информации -уровн  шума и относительного уровн  эхо-сигнала. Способ заключаетс  в термической обработке оксидов трёхвалентного и шестивалентного хрома в присутствии воды при температуре 300-350°С и давлении 200-400 бар соединений сурьмы и игольчатых частиц оксидов железа. При этом в качестве соединений сурьмьи используют виннокислую сурьму или виннокислую сурьм нркалиевую соль. 2 табл. This invention relates to a process for the production of ferromagnetic chromium dioxide used for the manufacture of magnetic storage media. The aim of the invention is to improve the electroacoustic properties of magnetic information carriers — the level of noise and the relative level of the echo signal. The method consists in thermally treating oxides of trivalent and hexavalent chromium in the presence of water at a temperature of 300-350 ° C and a pressure of 200-400 bar of antimony compounds and needle-like particles of iron oxides. At the same time, antimony tartrate or tartrate acid is used as antimony compounds. 2 tab.

Pigment composition based on hydrated chromium oxide with a reduced chromium (VI) content, useful in the preparation of cosmetic compositions

A pigment composition comprises particles(p) based on chromiun oxide in which chromium in the oxidation state (VI) is present at no more than 5 ppm relative to the total mass of particles(p). Independent claims are also included for the preparation of the composition and its use.

Patent FR2486061B1

Ferromagnetic crystalline chromium dioxide - esp for use in magnetic tapes

Title compsn. is prepd. by (a) thermally decomposing an org. chromium salt under an inert, opt. wet atmos., (b) oxidising the decomposed pdt. under controlled conditions, and (c) crystallising the oxidised pdt. under an oxygen pressure >32 bars, and at such a temp. that the corresponding point, in a graphical system whose coordinates are the oxygen pressure and the temp, is situated in the stability range of chromium dioxide.

Patent FR2181888A1

Process and apparatus for the manufacture of chromium oxide

PROCESS FOR THE PRODUCTION OF AN IRON FREE CHROME III COMPOUND

PROCEDE POUR LA PREPARATION D'UN COMPOSE DE CHROME III ESSENTIELLEMENT EXEMPT DE FER, A TEMPERATURE ET PRESSION ELEVEES, A PARTIR D'UNE SOLUTION AQUEUSE ACIDE CONTENANT DU FER ET DU CHROME, PROCEDE CARACTERISE EN CE QUE, AFIN D'EMPECHER LA COPRECIPITATION DU FER, UN ADDITIF EST AJOUTE A L'ETAPE DE PRECIPITATION, L'ADDITIF FORMANT DANS LES CONDITIONS DE PRECIPITATION AU MOINS 2G1 DE CHROME BIVALENT DANS LA SOLUTION. PROCESS FOR THE PREPARATION OF A ESSENTIALLY IRON-FREE, HIGH TEMPERATURE AND PRESSURE CHROMIUM III COMPOUND FROM AN ACID ACID SOLUTION CONTAINING IRON AND CHROME, CHARACTERIZED IN THAT IN ORDER TO PREVENT THE COPRECIPITATION OF THE IRON, AN ADDITIVE IS ADDED TO THE PRECIPITATION STAGE, THE ADDITIVE FORMING IN THE PRECIPITATION CONDITIONS AT LEAST 2G1 OF BIVALENT CHROME IN THE SOLUTION.

Elimination of hexavalent chromium - from wastes by hypophosphite in acid medium

Process for the preparation of stabilized acicular ferromagnetic chromiumdioxide

This chromium dioxide is prepared by a finishing treatment of the surface of the chromium dioxide formed by a reductive treatment using adsorbed mono- or polybasic hydroxy carboxylic acids.

Continuous synthesis of chromium dioxide

Ferromagnetic chromium dioxide is produced in a continuous operation by feeding a preheated paste of hydrated chromium oxides and additives into a twin screw reactor, reacting at elevated temperature and pressure for a short time while venting oxygen and steam, injecting water near the end of the reaction zone to form a viscous chromium dioxide-water mixture, and cooling while passing through a pressure letdown extruder.

FRAMEWORK FOR FRAMSTATING AV AND JAERNFRI KROM (III) FOERENING

Magnetic recording material.

Chromium hydroxide green

A kind of method for cleaning static continuous and automatic calcining production chrome oxide green

本发明公开了一种清洁静态连续自动化煅烧生产氧化铬绿的系统及方法包括：通过螺旋机输送机原料氢氧化铬输送至装料机，使位于滚筒输送机的料钵平铺于装料机的下料口，经装料机计量后装于料钵中；通过滚筒输送机将装有氢氧化铬的料钵输送至辊道窑，于窑炉内经预热、煅烧、冷却阶段，以电加热提供热源，控制煅烧温度950～1200℃，恒温0.5～4h；冷却阶段以循环水为冷却介质，出窑料钵温度＜35℃；将辊道窑输送出的料钵通过滚筒输送机输送至真空吸料机位置，将真空吸料机的吸管定位于料钵中，真空吸料机将煅烧得到的氧化铬绿输送至包装系统；料钵继续由滚筒输送机输送至装料机位置进行循环煅烧操作。

PROCEDURE FOR THE PRODUCTION OF FERROMAGNETIC CHROME Dioxide.

Magnetic tape and method of manufacturing same

Manufacture of highly coercive chromium dioxide

1345039 Chromium dioxide BADISCHE ANILIN- & SODA-FABRIK AG 10 May 1971 [11 May 1970] 13959/71 Heading C1A [Also in Division H1] Ferromagnetic chromium dioxide is made by heating chromium trioxide at 250-500‹ C. and 50-3000 ats. in presence of water, acicular crystals of iron and/or iron oxides (0À1-10 wt. per cent based on CrO 3 ) and at least one other modifying element (in elemental or compound form). The total amount of modifying elements (calculated as elemental form) present may be 0À2-25 wt. per cent based on CrO 3 . Specified foreign elements are metals of Groups 5A and 6A, P, As, Sb, Se, Te and Ni. The iron may be present as γ-Fe (III) oxide or α-FeOOH (2À5:1 to 10:1 aspect ratio, 0À4-1 Á). The chromium dioxide may be made by a one-stage process, involving heating CrO 3 , H 2 O and additives at 280-350‹ C. and 150-700 ats. for 1 to 10 hours. Alternatively, in a two-stage process, the CrO 3 is heated to 300-360‹ C. for 30-60 mins., and then 280-500‹ C. for 10 mins to 10 hours, a pressure of 50-300 ats. being maintained in the latter stage, and the foreign elements being added at either stage. In examples, the modifying compounds are (1) TeO 2 +γ-Fe 2 O 3 ; (2) Sb 3 O 3 +α-FeOOM; (3) TeO 2 +α-FeOOM; (4) TeO 2 +Fe; (5) Sb 2 O 3 +α-Fe 2 O 3 ; (6) Sb 2 O 3 + γ-Fe 2 O 3 .

FERROMAGNETIC COMPOSITION CONSISTING OF MODIFIED FERROMAGNETIC CHROME DIOXIDE AND METHODS OF PREPARING THE SAME

STABILIZED FERROMAGNETIC CHROME BIOXIDE AND ITS PREPARATION PROCESS

L'invention a pour objet un bioxyde de chrome stabilisé et son procédé de préparation. Le produit stabilisé comprend du CrO2 dont les particules sont enrobées avec un polyphosphate de Zn, Al ou Cr de formule : The invention relates to a stabilized chromium dioxide and its preparation process. The stabilized product comprises CrO2, the particles of which are coated with a polyphosphate of Zn, Al or Cr of the formula:

Magnetic recording media for longitudinal recording

A magnetic recording medium for longitudinal recording with a low media noise, a high S/N ratio and high reliabilities in corrosion resistance is disclosed. By making a magnetic layer from a Co-based alloy comprising 1 to 35 at. % of at least one element selected from the group consisting of Pt and Ir, 1 to 17 at. % of at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ge and Si, except for Si, whose concentration is 1 to 40 at. %, and 0.1 to 10 at. % of oxygen, a magnetic recording medium for longitudinal recording having an inplane coercivity of 1,200 Oe or more and a coercive squares of not more than 0.85 is obtained.

Method for raising the curie point of ferromagnetic chromium dioxide

Method for regenerating pickling acids

METHOD FOR REGENERATING PICKLING ACIDS Abstract of Disclosure The residual acid mixture containing metals which has been produced in the steel pickling process is regenerated to become new HF/HNO3 pickling acid by applying H2SO4 addition and evaporation. The metal sulphate salt produced in evaporation is converted into scarcely soluble iron jarosite Na[Fe3(SO4)2(OH)6] and chrome and nickel hydroxide, the last mentioned metal hydroxide being obtained as a separately utilizable precipitate. The metal sulphate salt is separated from 60% H2SO4 solution, wherein the main part of the salt is also crystallized. For promoting the crystallization, part of the salt is crystallized in a side line where 80% H2SO4 concentration is used. The acid slurry produced is carried back to the crystallizing stage in the main line.

Process for the preparation of ferromagnetic chromium dioxide

1287614 Chromium oxide FARBENFABRIKEN BAYER AG 7 Oct 1969 [11 Oct 1968] 49137/69 Heading C1A [Also in Division H1] Ferromagnetic CrO 2 is made by (1) heating CrO 3 with a modifier to 200-380‹ C. to form a chromium oxide in which the chromium has an average valency of above 4 but below 6; (2) heating this chromium oxide with CrO 3 in the presence of water to 200-400‹ C. at a pressure of 1 to 500 kg./cm.<SP>2</SP>, using 1-40% wt. per cent of the chromium oxide product of (1) based on the weight of CrO 3 used in the second stage. The modifier, which may comprise 1-30 wt. per cent of the CrO 3 used in stage (1), may be tellurium or tellurium and/or antimony compounds with or without iron oxides or hydroxides. In examples, the products from stage (1) are Cr 3 O 8 or a mixture of Cr 3 O 8 and Cr 2 O 5 modified with TeO 2 , Sb 2 O 3 or α-FeOOH. The CrO 2 products may have a remanence of 400-500 Gauss cm.<SP>3</SP>g.<SP>-1</SP> and a coercivity of 200-500 Ve and consist of acicular particles 0À1-2 Á x 0À02-0À1 Á.

Modified ferromagnetic chromium dioxide composition and method of preparing the same

FOERFARANDE FOER REGENERERING AV BETNINGSSYROR

MODIFIED FERROMAGNETIC CHROME DIOXIDE AND ITS PREPARATION PROCESS

Process for preparing low sulphur chromiumoxide*3*

METHOD FOR PRODUCING MODIFIED FERROMAGNETIC CHROMDIOXIDE

Process for producing ferromagnetic chromium dioxide, and its use in producing magnetic recording carriers

Die Erfindung betrifft ein Verfahren zur Herstellung von mit Fremdelementen modifiziertem ferromagnetischem Chromdioxid durch Umsetzen von Oxiden des 3-wertigen und 6-wertigen Chroms bei erhöhtem Druck und erhöhter Temperatur in Gegenwart von Wasser unter Zusatz von zumindest Antimon (III) oxid als Modifizierungsmittel sowie gegebenenfalls weiterer Zusatzstoffe in einer 15 Gew.% nicht übersteigenden Menge, wobei das als Modifizierungsmittel eingesetzte Antion (III)- oxid zu mehr als ein Drittel in der kubischen Modifikation des Senarmontit vorliegt, eine spezifische Oberfläche nach BET zwischen 1,5 und 15 m²/g aufweist und in einer Gesamtmenge von kleiner 0,5 Gew.%, bezogen auf das resultierende Chromdioxid, zugesetzt wird sowie seine Verwendung zur Herstellung von magnetischen Aufzeichnungsträgern. The invention relates to a process for the production of ferromagnetic chromium dioxide modified with foreign elements by reacting oxides of trivalent and hexavalent chromium at elevated pressure and elevated temperature in the presence of water with the addition of at least antimony (III) oxide as modifying agent and optionally further Additives in an amount not exceeding 15% by weight, more than a third of the anion (III) oxide used as modifier being in the cubic modification of the senarmontite, has a BET specific surface area of between 1.5 and 15 m² / g and is added in a total amount of less than 0.5% by weight, based on the resulting chromium dioxide, and its use for the production of magnetic recording media.

Ferromagnetic chromium dioxide crystals

Half to charles y

Process for preparing ferromagnetic chromium dioxide

ABSTRACT OF THE DISCLOSURE Ferromagnetic chromium dioxide is prepared by ther-mally decomposing, at a temperature of 250-500°C, and a pressure of at least 80 atmospheres a mixture of hydrated trivalent chromium chromate of the formula Cr2(CrO4)3. nH2O, wherein n is 8-12, and antimony or a compound thereof, the amount of antimony in the mixture being between 0.3 and 0.7% by weight based on the weight of anhydrous Cr2(CrO4)3. In another embodiment, other known modifiers for chromium dioxide, such as lanthanum, lithium, strontium, iron or lead, or a compound thereof may be added to the mixture of chromium chromate and antimony. The amount of said other modifiers is between 0.1 and 2% by weight of the ele-ment, based on the weight of anhydrous Cr2(CrO4)3.

Magnetic recording medium

(57)【要約】本公報は電子出願前の出願データであるた め要約のデータは記録されません。

Ferromagnetic chromium oxide and preparation

PROCEDURE FOR THE STABILIZATION OF MAGNETIC PIGMENTS WITH CHROMIUM DIOXIDE

Magnetic record carrier

Modified ferromagnetic chromium dioxide composition and process for its preparation

Production of a substantially iron-free chromium (III) compound

A chromium (III) compound containing very little iron compound contaminant is selectively precipitated from a mixture of iron and chromium compounds in aqueous acid solution by use of an elevated temperature and pressure, the acid aqueous solution of iron and chromium compounds containing at least 2 g/l of bivalent chromium.

Sedimentation of iron-free chromium(iii) compound

Ferromagnetic material

Iron containing ferromagnetic chromium oxide

FERROMAGNETIC CHROMIUM OXIDE HAVING AN INTRINSIC COERCIVE FORCE ABOVE 600 OERSTEDS IS PREPARED BY HEATING AN INTIMATE MIXTURE OF CHROMIUM (III) AND IRON (III) COMBINED WITH OXYGEN WITH AN OXIDIZING AGENT. IN PARTICULAR EMBODIMENTS, THE MIXTURE IS OBTAINED BY CO-PRECIPITATION OF THE HYDROXIDES FROM A SOLUTION OF CHROMIUM (III) AND IRON (III) SALTS.

Magnetic materials

1370931 Magnetic chromium oxide MATSUSHITA ELECTRIC INDUSTRIAL CO Ltd 22 Sept 1971 [22 Sept 1970] 44209/71 Headings C1A and C1J A ferromagnetic chromium oxide material comprises 61À90-57À22 wt. per cent chromium and 0À0038-15À10 wt per cent sulphur, the balance being oxygen. The material may be made by mixing chromium trioxide and sulphur in the required proportions and heating the mixture at 50-1000 atmospheres and 250- 480‹ C. The mixture may be heated, with or without a small amount of water, in a crucible of glass, ceramic or metal (other than iron).

METHOD FOR STABILIZING MAGNETIC CHROME DIOXIDE PIGMENTS AND NON-LAYERED MAGNETOGRAM CARRIER, MANUFACTURED THEREOF

Patent FR2088492B1

Patent FR2108364A5

Method for improving color of chromium oxide green

本发明提供了一种改善氧化铬绿色泽的方法，所述方法包括：将重铬酸盐与还原剂混合后在氧化性气氛中焙烧，得到焙烧尾气和氧化铬绿产品，焙烧过程中控制焙烧尾气中氧气的浓度不低于11vol.％。本发明所述方法基于重铬酸盐还原法制备氧化铬绿的生产工艺，通过进一步控制焙烧气氛，即可得到高性能颜料级氧化铬绿产品；本发明所述方法操作简单，不影响设备产能，对生产成本的影响也较小，有利于工业化规模生产，具有较好的工业应用前景。

Patent FR2433483B2

Chromium dioxide mfr - in an autoclave with a disposable interior cylinder

Ferromagnetic CrO2 and modified CrO2 (with an additive) are produced in an autoclave having two interior cylinders, the inside one of which can easily be cut up to remove lumps of the CrO2. Ferromagnetic CrO2 and the modified form are useful as recording dispersions that can be magnetised, e.g. in magnetic recording tape.

CHROME OXIDE FOR THE FIREPROOF INDUSTRY

Continuous process for the removal of chromium from waste waters and valorization of the recovered chromium

A continuous process is described, wherein chromium-containing waste waters are subjected to continuous hot treatment with acetic acid or with alkaline acetates and alkaline hydroxides at a temperature from 40 DEG C. to boiling point and at atmospheric pressure, at a pH higher than 6.5, preferably between 7 and 10, particularly about 7.5. Thus, a "sandy" type of chromium hydroxide is obtained, having a titer in Cr2O3 of 20 to 40% by weight, which quickly filters, is easily soluble in acids, and thereby affords an easy valorization both as a tanning agent and as a raw material for preparing other chromium compound.

IMPROVED CHROMOXIDE GREEN, METHOD FOR THE PRODUCTION THEREOF AND THE USE THEREOF.

The present invention relates to an improved green chromium oxide in which the particles predominantly consist of rings or hoops and to a process for its preparation and its use.

METHOD FOR REGENERATING STRIPPING ACIDS

Production of low sulphur chromium (III) oxide

A process for the production of low sulphur chromium(III) oxide comprising annealing at a calcining temperature from about 800° C. to 1100° C. a mixture of alkali metal chromate and about 0.7 to 0.96 times its molar amount of ammonium sulfate, and separating the chromium(III) oxide formed from the alkali metal salt. Advantageously the ammonium sulfate in the form of a concentrated solution is mixed with solid alkali metal dichromate and the mixture thereafter is adjusted prior to calcination to a water concentration of less than about 15% by weight of water.

Master and copy tape system for thermomagnetic copying - contg. magnetic pigment with higher Curie temp. in master tape and limited butyl palmitate concn.

Magnetic tape (MT) for thermomagnetic copying contains a magnetic pigment (I-M) with Curie temp. TC1 and copy tape (CT) a magnetic pigment (I-C) with Curie temp. TC2, both finely dispersed in polymeric binder. For copying, CT is heated to a temp. above TC2 but below TC1 and then cooled in close contact with MT. MT and/or CT contains fatty acid and/or fatty ester with a butyl palmitate (II) fraction as lubricant. The novelty is that the (II) content of MT and/or CT is max. 0.15 g/100g (I). Pref. (I-M) consists of metal (alloy) powder with a coercivity of min. 100 kA/m and TC1 greater than 300 deg.C; and (I-C) or CrO2 with a coercivity of min. 40 kA/m and TC2 ca. 130 deg.C. USE/ADVANTAGE - The system is useful for video purposes. The tapes are suitable for high speed copying. MT still has satisfactory running properties after several thousand passes and transfers the information to TC without loss or distortion, even after prolonged use.

Manufacture of pigments

Process for the preparation of ferromagnetic chromium dioxide

Ferromagnetic chromium dioxide magnetic - recording elements

Patent FR2104656B1

Tape media having synergistic magnetic recording layer and underlayer

A product, according to one approach, includes an underlayer and a magnetic recording layer formed above the underlayer. The underlayer includes first encapsulated nanoparticles each comprising a first magnetic nanoparticle encapsulated by a first aromatic polymer, and a first polymeric binder binding the first encapsulated nanoparticles. The recording layer includes second encapsulated nanoparticles each comprising a second magnetic nanoparticle encapsulated by an encapsulating layer, and a second polymeric binder binding the second encapsulated nanoparticles.

MAGNETIC REGISTRATION ELEMENT.

Chormia spray powders and a process for making the same

Chromium oxide magnetic powder production plant

Chromium oxide magnetic powder production plant Abstract 5 Chromium oxide magnetic powder production plant, including: reactor (DI01), stirring reactor (D102), filter (LIO), scrubber (L102), dryer (L103), tank (F101), pump (J101); among them, pump (JIO) is connected respectively to tank (FlOl) and reactor (D101), stirring reactor (D102) is connected respectively to reactor (D101) and filter (L1O); among them, nominal volume of stirring reactor (D102) is 10 800-900L. Figure 1 a 4-) o - 4-) Ci to * 0 o 4-' * 0 'S -ci - 4-) .~ ~.- En C 4-> = 'S -' Cs -ci -z 47-A C) >5 -'2 S t -- [~ - - - -*,--~~ <10 'S I Ci 4-) 0 - ~ - C 0 - ci 4-)!! C L~!4-.~ to 0 C-S O.fl L+4 II ~ K-> Figure

Patent CH617910A5

Flexible multi-layer magnetic recording media

Flexible multi-layer magnetic recording media comprising a non-magnetic flexible base and, applied thereto, two superposed magnetizable layers which contain a homogeneous mixture of acicular magnetic chromium dioxide in an organic binder. According to the invention, the magnetizable layer adjacent to the base contains a chromium dioxide having a specific surface area, measured by the BET method, of from 15 to 25 m 2 /g, while the outer magnetic layer contains a chromium dioxide having a specific surface area, measured by the BET method, of from 26 to 35 m 2 /g. Such magnetic recording media are distinguished by uniformly high sensitivity over the entire audible frequency range even if close manufacturing tolerances are not maintained.

A kind of chromium salt production method that supplies are recyclable

本发明公开了一种辅助物料可循环的铬盐生产方法，包括如下步骤：(1)生料配置；(2)氧化焙烧转型；(3)熟料铵盐浸出；(4)除杂结晶；(5)铬酸铵盐分解；(6)将步骤(2)、(4)、(5)后得到的氨气和/或二氧化碳用溶液进行吸收，得到铵盐溶液作为浸出剂循环利用。本发明的铬盐生产方法，摒弃了采用碱金属的碳酸盐或氢氧化物作为氧化分解铬铁矿的辅助物料，采用低成本、易循环的碳酸钙等含钙物料和铵盐作为铬盐生产的辅助物料，避免了铬盐生产大量碱的消耗，根除了含铬芒硝等含铬废渣的排放问题，经济高效地实现了铬盐生产过程辅助物料的循环，减少铬盐生产过程的物料消耗，降低生产成本和环境污染，得到的铬盐产品质量高。

Recovery of chromium values from waste streams by the use of alkaline magnesium compounds

A process and a product formed thereby for the recovery of chromium values from aqueous solutions (e.g., waste liquors) comprises contacting an acidic solution containing sulfate ion and trivalent chromium ion with at least about 4 molar equivalents of MgO or Mg(OH) 2 per 3 molar equivalents of trivalent chromium in addition to the amount required to neutralize the free acid to a pH of about 4 to form an amorphous, dense solid, grainy, easily settleable, trivalent chromium-containing precipitate in an alkaline solution according to the equation: 3Cr 2 (SO 4 ) + 8 MgO →Cr 2 (OH) 4 SO 4 · 4Cr(OH) 3 · 4H 2 O + 8 MgSO 4 . The trivalent chromium-containing product can be readily separated from the water and is a useful source of chromium for subsequent processing. The water remaining after separation of the precipitate contains less than 0.5 mg/l chromium.

Process of preparing chromic oxide

MAGNETIC RECORDING CARRIER

Magnetic data carriers

Process for treating chromium dioxide

PROCESS FOR TREATING CHROMIUM DIOXIDE ABSTRACT OF THE DISCLOSURE Ferromagnetic chromium dioxide is normally produced using other chromium com-pounds as starting materials. In most reactions a Cr(VI) compound, such as chromium trioxide is used in some stage of the procedure. Following the conversion reaction there are inevitably small amounts of the original chromium (VI) ions in the form of salts or oxide compounds which are strongly adsorbed on or attached to the chromium dioxide in a manner which prevents them from being easily removed by normal washing techniques. These Cr(VI) ions, if left in the chromium dioxide can cause problems. These disadvantages have now been overcome by treating the impure chromium dioxide with a peroxide compound in a manner which causes the Cr(VI) ions to change their character and allow their removal from the chromium dioxide.

Ferromagnetic chromium dioxide prepn

Chromium dioxide having a tetragonal crystal structure of the rutile type is prepd. by heating a compound containing chromium of valency more than 4 e.g. CrO3 to between 320 and 450 degrees C at a pressure of 1-100 atmospheres in the presence of 0.1-10% of a crystal nucleus of e.g. CrO2, TiO2, CrSbO4. Oxides or salts of other metals e.g. SbCl3, Li2CO3, Sb2O3 may also be present. The magnetic properties of the chromium dioxide obtained in this way are particularly high.

Process for reprocessing chromium(VI)-containing solutions

The present invention relates to a process for reprocessing chromium(VI)-containing solutions by approximately stochiometric reduction with sulphur dioxide, followed by alkaline precipitation of the chromium(III) hydroxide in which process the chromium(VI)-containing solution to be reprocessed is treated with sulphur dioxide in a plurality of reduction stages and then, after a post-reaction time sufficient for complete reduction, the chromium(III) formed is precipitated as the hydroxide, with the addition of alkaline substances, and is separated.

Process for the production of chromic hydroxide

Sodium or potassium monochromate solutions are reduced with sodium or potassium monosulphide, yielding chromic hydroxide, alkali sulphate and alkali hydroxide. The latter is separated and used in known methods of chromate production or other well-known technical applications, if desired after conversion to carbonate, bicarbonate, acetate or the like. The precipitated chromic hydroxide may be ignited e.g. at 900 DEG C. to yield a pigment or converted into soluble chromium salts by adding the appropriate acid. The Specification as open to inspection under Section 91 describes also the reduction of chromates and dichromates of ammonium, calcium, strontium, barium, magnesium or lead by sulphides, or their oxidation products, e.g., thiosulphates or polythionates. This subject matter does not appear in the Specification as accepted. Reference has been directed by the Comptroller to Specifications 18,743/98, [Class 41], and 336,671, [Class 1 (iii)]

Processing of chromium ore

Method of preparing ferromagnetic chromium dioxide

PROCESS FOR THE PREPARATION OF IMPROVED CHROME BIOXIDE AND CHROME BIOXIDE THUS OBTAINED

Stabilisation of ferromagnetic chromium di:oxide - by coating with an orthophosphate or hydroxide of zinc, aluminium or chromium

Chromium dioxide material, process for its preparation and magnetic recording material containing this chromium dioxide material

The invention relates to a chromium dioxide material, consisting of needle-shaped, ferromagnetic chromium dioxide particles having a non-magnetic, hydrogenous surface protective layer, which is distinguished by an improved stability against chemical decomposition, a process for its preparation and magnetic recording material containing this chromium dioxide with high long-term climatic stability of the remanent magnetisation.

Recovery of vanadium and chromium

Process for treating alkali metal chromates