DOCSLIB.ORG

A Fundamental Study of Copper and Cyanide Recovery from Gold Tailings by Sulfidisation

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
A Fundamental Study of Copper and Cyanide Recovery from Gold Tailings by Sulfidisation Western Australian School of Mines Department of Metallurgical and Minerals Engineering A Fundamental Study of Copper and Cyanide Recovery from Gold Tailings by Sulfidisation Andrew Murray Simons This thesis is presented for the Degree of Doctor of Philosophy of Curtin University June 2015 STATEMENT OF AUTHENTICITY To the best of my knowledge and belief this thesis contains no material previously published by any other person except where due acknowledgment has been made. This thesis contains no material which has been accepted for the award of any other degree or diploma in any university. Andrew Murray Simons i ABSTRACT Cyanide soluble copper in gold ores causes numerous problems for gold producers. This includes increased costs from high cyanide consumption and a requirement to destroy cyanide in the tailings before discharge into a tailings storage facility. Over recent years a cyanide recycling process known as SART (sulfidisation, acidification, recycle, and thickening) has gained attention as a method to remediate the increased costs and potential environmental impact caused by using cyanidation to process copper bearing gold ores. While sulfidisation processes, such as SART, have been demonstrated within the laboratory to be effective, there are several gold processing operations using sulfidisation which report high sulfide consumption compared to the expected reaction stoichiometry. Further to this problem, there is a lack of fundamental studies of sulfidisation of cyanide solutions resulting in a poor understanding of how various process variables impact the process. This thesis details work on sulfidisation of copper cyanide solutions to systematically determine the impact of process variables and impurities on the SART process. The work is divided into three distinct areas: modelling of process variables on sulfidisation performance, impact of impurities in sulfidisation, and the impact of residence time on sulfidisation. Mathematical modelling of sulfidisation of the copper, cyanide, and sulfide system was performed to determine the impact of various factors on sulfidisation. An economic model was then used to determine the overall process optimum and system sensitivity at suboptimal operation. The model showed that to maximise profit during sulfidisation, a sulfide addition of 0.56 moles per mole of copper, a pH of 4, and the lowest possible cyanide to copper ratio should be used. These optimum conditions to maximise profit ii remained the same within the range of reagent costs and product values used in the study. The model also showed that it is critical to control sulfide addition at its optimum value, and that the cyanide to copper ratio in the sulfidisation feed should be kept as low as possible, depending on upstream processing constraints. Impurities in the sulfidisation feed have numerous impacts on sulfidisation performance. It was found that silver and zinc have the largest impact on copper recovery as these two metals consume sulfide preferentially to copper. Gold, iron, nickel, thiosulfate, thiocyanate, and chloride all had no major impact on sulfidisation of copper cyanide solutions. These species did, however, have different minor effects on the process ranging from increases in acid consumption through to shifting the pH range of copper precipitation. It was found that copper can be selectively recovered from other metals, although a small amount of co-precipitation/adsorption occurs. Hence, complete separation of other metals from copper is not possible during sulfidisation. When sulfidisation is performed on mixed metal cyanide solutions, there are various complex interactions which occur. This includes the potential to precipitate gold at a higher pH than when other metals are not present, likely due to the formation of a silver gold sulfide precipitate. Selective recovery of various metals in sulfidisation is possible, although a small amount of co- precipitation/adsorption will always occur. In any case, selective precipitation would require tight control of sulfide addition and pH. The most intriguing result from the work is the discovery that long residence times during sulfidisation are the cause of high sulfide consumption experienced in some industrial sulfidisation processes. This is due to iii oxidation of the sulfidisation precipitate from a structure similar to Cu2S towards that of CuS. Ultimately, if excess sulfide is not present in solution, copper redissolution occurs reducing the recovery of both copper and cyanide in the process. Industrial surveys of an operational sulfidisation process, along with laboratory scale work using industrial solutions, confirmed the observations from the test work with synthetic copper cyanide solutions. Interestingly, the composition of the industrial solution results in a higher rate of oxidation compared to the synthetic solutions. iv ACKNOWLEDGEMENTS I would firstly like to thank my supervisors Dr Richard Browner from the Western Australian School of Mines (WASM) and Dr Paul Breuer from CSIRO. Both Richard and Paul never ceased to inspire my interest and curiosity in hydrometallurgy and science in general. I extend many thanks to all of the CSIRO Waterford site staff and fellow PhD students from WASM who have assisted me during my candidature. Of particular mention is Danielle Hewitt whom has assisted me in many aspects of my laboratory work. I’d also like to extend thanks to the Newcrest Telfer metallurgical staff for their assistance in surveying the Telfer SART plant. I would like to mention the support of my loving parents who have encouraged me over the past four years of my candidature. I am very thankful to have inherited the scientific rational of my father and the creativity of my mother. Finally, I would like to acknowledge and thank both the CSIRO Minerals Down Under Flagship and the Parker Cooperative Research Centre for Integrated Hydrometallurgy Solutions for their financial support during my candidature. v CONTENTS Statement of authenticity ........................................................................................ i Abstract ...................................................................................................................... ii Acknowledgements ................................................................................................. v Contents .................................................................................................................... vi Publications ............................................................................................................. xii List of figures ......................................................................................................... xiv List of tables ...................................................................................................... xxviii 1 Introduction ....................................................................................................... 1 1.1 Importance of gold .................................................................................... 1 1.2 Processing gold ores ................................................................................. 3 1.2.1 History of gold processing ................................................................... 3 1.2.2 Gold cyanidation ................................................................................... 4 1.2.3 The impact of copper in gold cyanidation ......................................... 6 1.3 Mitigating the effect of copper in gold processing ............................... 8 1.3.1 Selective leaching of gold ..................................................................... 9 1.3.2 Selective leaching of copper................................................................. 9 1.3.3 Cyanide destruction ............................................................................ 10 1.3.4 Cyanide recycling ................................................................................ 11 1.3.5 Copper recovery and cyanide recycling by sulfidisation .............. 12 1.4 Objectives ................................................................................................. 16 1.5 Thesis structure ....................................................................................... 17 2 Minimising the impact of copper in gold cyanidation ............................ 19 2.1 Thermodynamic modelling ................................................................... 19 2.2 Comparison of technology for separating copper and cyanide ....... 19 2.2.1 Direct recycle........................................................................................ 24 2.2.2 Volatilisation ........................................................................................ 25 2.2.3 Copper cyanide digestion .................................................................. 27 vi 2.2.4 Sulfidisation ......................................................................................... 28 2.3 Factors impacting copper-cyanide-sulfide chemistry ........................ 30 2.3.1 The sulfide system............................................................................... 30 2.3.2 Effect of pH .......................................................................................... 32 2.3.3 Effect of sulfide to copper ratio ......................................................... 38 2.3.4 Effect of cyanide to copper ratio ....................................................... 43 2.3.5 Effect of volatilisation ........................................................................
Load more

Recommended publications
  • Significance of Mineralogy in the Development of Flowsheets for Processing Uranium Ores
    JfipwK LEACHING TIME REAGENTS TEMPERATURE FLOCCULANT CLARITY AREA COUNTER CURRENT DECANTATION It 21 21 J^^LJt TECHNICAL REPORTS SERIES No.19 6 Significance of Mineralogy in the Development of Flowsheets for Processing Uranium Ores \W# INTERNATIONAL ATOMIC ENERGY AGENCY, VIENNA, 1980 SIGNIFICANCE OF MINERALOGY IN THE DEVELOPMENT OF FLOWSHEETS FOR PROCESSING URANIUM ORES The following States are Members of the International Atomic Energy Agency: AFGHANISTAN HOLY SEE PHILIPPINES ALBANIA HUNGARY POLAND ALGERIA ICELAND PORTUGAL ARGENTINA INDIA QATAR AUSTRALIA INDONESIA ROMANIA AUSTRIA IRAN SAUDI ARABIA BANGLADESH IRAQ SENEGAL BELGIUM IRELAND SIERRA LEONE BOLIVIA ISRAEL SINGAPORE BRAZIL ITALY SOUTH AFRICA BULGARIA IVORY COAST SPAIN BURMA JAMAICA SRI LANKA BYELORUSSIAN SOVIET JAPAN SUDAN SOCIALIST REPUBLIC JORDAN SWEDEN CANADA KENYA SWITZERLAND CHILE KOREA, REPUBLIC OF SYRIAN ARAB REPUBLIC COLOMBIA KUWAIT THAILAND COSTA RICA LEBANON TUNISIA CUBA LIBERIA TURKEY CYPRUS LIBYAN ARAB JAMAHIRIYA UGANDA CZECHOSLOVAKIA LIECHTENSTEIN UKRAINIAN SOVIET SOCIALIST DEMOCRATIC KAMPUCHEA LUXEMBOURG REPUBLIC DEMOCRATIC PEOPLE'S MADAGASCAR UNION OF SOVIET SOCIALIST REPUBLIC OF KOREA MALAYSIA REPUBLICS DENMARK MALI UNITED ARAB EMIRATES DOMINICAN REPUBLIC MAURITIUS UNITED KINGDOM OF GREAT ECUADOR MEXICO BRITAIN AND NORTHERN EGYPT MONACO IRELAND EL SALVADOR MONGOLIA UNITED REPUBLIC OF ETHIOPIA MOROCCO CAMEROON FINLAND NETHERLANDS UNITED REPUBLIC OF FRANCE NEW ZEALAND TANZANIA GABON NICARAGUA UNITED STATES OF AMERICA GERMAN DEMOCRATIC REPUBLIC NIGER URUGUAY GERMANY, FEDERAL REPUBLIC OF NIGERIA VENEZUELA GHANA NORWAY VIET NAM GREECE PAKISTAN YUGOSLAVIA GUATEMALA PANAMA ZAIRE HAITI PARAGUAY ZAMBIA PERU The Agency's Statute was approved on 23 October 1956 by the Conference on the Statute of the IAEA held at United Nations Headquarters, New York; it entered into force on 29 July 1957.
    [Show full text]
  • GEM FOCUS August 2020
    GEM FOCUS August 2020 GOLDSTONE, SUNSTONE, AVENTURESCENCE; A SPARKLING ENIGMA OF CENTURIES... emstones with unusual optical effects are know as sunstone feldspar today. Goldstone is cre - defined as phenomenal gems. Their unusual ated by mixing microscopic copper platelets into Geffect can designate a variety within a molten glass. The sheen and earthy color of this species and add value. i.e., star sapphire. Synthetic material was ideal for Italian mosaics and more counterparts or simulants are often seen, especially affordable jewelry, whereas much larger blocks when the natural counterpart is particularly valuable were used to create ornamental objects such as such as natural alexandrite and color change syn - snuff bottles, small bowls or carved figurines. A thetic sapphire. Aventurescence is a phenomenon common story to its origin purports that the Italian caused by light reflecting micro platelets in a gem glass producers discovered this particular effect by and is easily recognizable from the glittering sheen- accident, but when this was is not clear. Accounts like effect. While green mica crystals in quartz cre - of the first production date vary from one source to ates aventurine quartz, hematite and ilmenite crys - another and are stated as from 11th century to 13th tals create the same effect in sunstone feldspar. century. It is true that this rather attractive Murano glass with reddish brown speckles was a popular Out of all the phenomena seen in gems, aventures - and expensive glass production in Italy for many cence, especially the yellow-brown type, has been centuries but it is hard to believe that sunstone the subject of a long-standing discussion.
    [Show full text]
  • Curbing Illicit Mercury and Gold Flows in West Africa: Options for a Regional Approach
    Curbing Illicit Mercury and Gold Flows in West Africa: Options for a Regional Approach i INCLUSIVE AND SUSTAINABLE INDUSTRIAL DEVELOPMENT ii Curbing Illicit Mercury and Gold Flows in West Africa: Options for a Regional Approach iii November 2018 iv © UNIDO 2018. All rights reserved. This document has been produced without formal United Nations editing. The designations employed and the presentation of the material in this document do not imply the expression of any opinion whatsoever on the part of the Secretariat of the United Nations Industrial Development Organization (UNIDO) concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries, or its economic system or degree of development. Designations such as ‘developed’, ‘industrialized’ or ‘developing’ are intended for statistical convenience and do not necessarily express a judgement about the stage reached by a particular country or area in the development process. Mention of firm names or commercial products does not constitute an endorsement by UNIDO. Unless otherwise men- tioned, all references to sums of money are given in United States dollars. References to ‘tons’ are to metric tons, unless otherwise stated. All photos © UNIDO unless otherwise stated. Cover photo by Sadibou Sylla Acknowledgements This report was authored by Marcena Hunter of the Global Initiative Against Transnational Organized Crime. The report is part of the United Nations Industrial Development Organization (UNIDO) project, funded by the Government of Switzerland, to assist the Economic Community of West African States (ECOWAS) in its early implementation of the Minamata Convention. More information about the Minamata Convention and UNIDO’s work can be found on UNIDO’s website <https://www.unido.org/mercury> or by emailing Gabriela Eigenmann at [email protected].
    [Show full text]
  • S Ndlovu (PDF)
    Extraction of Gold Then, Now and the Future Prof Sehliselo Ndlovu DST/NRF SARChI: Hydrometallurgy and Sustainable Development University of the Witwatersrand, Johannesburg Building a Robust Minerals Industry 3 – 4 July 2017, Cresta Lodge, Harare University of the Witwatersrand Johannesburg Founded Oct. 1896: School of Mines Approx. 37 000 Students 5 Faculties, 33 Schools, 3610 Courses >160 000 Degrees Conferred since 1922 55% Female Students 10 National Centres of Excellence Home to the Bidvest Football Club( Current PSL league Champions) Evolution in Gold Processing Past Technologies • Amalgamation • Panning Current Technologies • Cyanide leaching • Processing of Emerging and Future refractory ores Technologies • Bio-oxidation • Ionic liquids • Alternative leaching • Ultrasonic leaching reagents • Corn starch?? Past Technologies Used in Ancient Times History of gold extends back at least 6,000 years. Egypt and Mesopotamia around 4000 BC. Gravity Separation: Gold Panning Gold concentrated by washing lighter river sands with water Leaves dense gold particles Alternative- wash gold-bearing sand and gravel over a woollen fleece Traps heavier gold dust that would sink into the wool fibres. Advantages • Simplicity Disadvantages • Labour intensive Gravity Separation: Sluicing • Water is channelled to flow through a sluice-box. • Sluice-box is essentially a man-made channel with riffles (barriers) at the bottom. • Riffles create dead-zones in the water current which allows gold to drop out of suspension. Sluicing and panning results in the direct recovery of small gold nuggets and flakes. Gold Parting: Salt Cementation Process • Invented to remove Ag from Au-Ag mixtures around 6th century BC. Mix: argentiferous gold foil, common salt, brick dust or burnt clay and urine in a sealed container.
    [Show full text]
  • Recovery of Gold and Iron from Cyanide Tailings with a Combined Direct Reduction Roasting and Leaching Process
    metals Article Recovery of Gold and Iron from Cyanide Tailings with a Combined Direct Reduction Roasting and Leaching Process Pingfeng Fu 1,2,* ID , Zhenyu Li 1, Jie Feng 1 and Zhenzhong Bian 1 1 School of Civil and Resources Engineering, University of Science and Technology Beijing, Beijing 100083, China; [email protected] (Z.L.); [email protected] (J.F.); [email protected] (Z.B.) 2 Key Laboratory of High-Efficient Mining and Safety of Metal Mines, Ministry of Education, Beijing 100083, China * Correspondence: [email protected]; Tel.: +86-10-6233-2902 Received: 25 June 2018; Accepted: 19 July 2018; Published: 21 July 2018 Abstract: Cyanide tailings are the hazardous waste discharged after gold cyanidation leaching. The recovery of gold and iron from cyanide tailings was investigated with a combined direct reduction roasting and leaching process. The effects of reduction temperature, coal dosage and CaO dosage on gold enrichment into Au-Fe alloy (FexAu1−x) were studied in direct reduction roasting. Gold containing iron powders, i.e., Au-Fe alloy, had the gold grade of 8.23 g/t with a recovery of 97.46%. After separating gold and iron in iron powders with sulfuric acid leaching, ferrous sulfate in the leachate was crystallized to prepare FeSO4·7H2O with a yield of 222.42% to cyanide tailings. Gold enriched in acid-leaching residue with gold grade of 216.58 g/t was extracted into pregnant solution. The total gold recovery of the whole process reached as high as 94.23%. The tailings generated in the magnetic separation of roasted products, with a yield of 51.33% to cyanide tailings, had no toxic cyanide any more.
    [Show full text]
  • Simulation Study of the Optimal Distribution of Cyanide in a Gold Leaching Circuit
    Minerals Engineering 19 (2006) 1319–1327 This article is also available online at: www.elsevier.com/locate/mineng Simulation study of the optimal distribution of cyanide in a gold leaching circuit L.R.P. de Andrade Lima a,b,*, D. Hodouin a a Department of Mining, Metallurgical, and Materials Engineering, Laval University, Quebec City, Canada G1K 7P4 b Department of Materials Science and Technology, Federal University of Bahia, C.P. 6974, Salvador, BA 40810-971, Brazil Received 25 September 2005; accepted 1 December 2005 Available online 19 January 2006 Abstract The mineral industry has been using cyanidation to recover gold from ores for more than a century; however, a systematic study of the best reactant addition strategy in a cascade of agitated leaching tanks is not available in the open literature. A phenomenological math- ematical model of the gold cyanidation process, calibrated with a set of industrial data from an Australian plant, together with an eco- nomic performance index is used to analyze this problem. The simulated results show that the best compromise between the two antagonistic effects, cyanide consumption and gold recovery, which are both function of cyanide concentrations, leads to a reagent dis- tribution that depends on the leaching and cyanide consumption kinetics, pulp feed characteristics, and economic factors such as the gold market value. For the specific studied plant, in the operating range of low cyanide consumption and fast gold dissolution, all the cyanide must be added in the first tank; however, in the operating conditions of high cyanide consumption, cyanide has to be distributed in the first, second and third tanks.
    [Show full text]
  • Got a Pocket Full of Sunstone? Maybe Think Twice
    Page 1 of 5 Got a pocket full of Sunstone? Maybe think twice Sunstone falls part of the Feldspar The larger and more abundant the mineral group. It is known for inclusions are, the more exhibiting what is called “Aventurescent” the stone will be “Aventurescence”. and the deeper the golden colour will appear. There are also transparent Sunstones from Oregon in the USA. They are often green and/or red in colour, with small copper inclusions (often in “streams”) creating a Aventurescence is a type of “Schiller” effect. iridescence (a play-of-colour) that is caused by the reflection of small, thin and platy inclusions - copper, goethite and/or hematite in the case of Sunstone - that are spread in a parallel orientation through the gem. This causes interference of light between the layers of platelets which creates the glittery sheen associated with Sunstone (see image on the above right). Kaylan Khourie, FGA All rights reserved. 08/09/2019 Page 2 of 5 Sunstone falls into three species Sunstone can fall into three species of the Feldspar group: Orthoclase, Oligoclase and Labradorite (this is also into where the Oregon material falls). Orthoclase falls under the “Alkali Feldspar” category whereas Oligoclase and Labradorite fall under the “Plagioclase Feldspar” category. Below is a table of each species of Sunstone and some of their properties: Specific Refractive Species Chemical Composition Birefringence Gravity Index Orthoclase KAlSi₃O₈ 2.58 1.518 - 1.526 0.005 -0.008 Solid solution between Oligoclase 2.65 1.539 - 1.547 0.007 - 0.010 NaAlSi₃O₈ and CaAlSi₂O₈ Solid solution between Labradorite 2.70 1.559 - 1.568 0.007 - 0.010 NaAlSi₃O₈ and CaAlSi₂O₈ ↳ Oregon Solid solution between 2.67 - 2.72 1.563 - 1.572 0.009 material NaAlSi₃O₈ and CaAlSi₂O₈ However, the gems being marketed as “Sunstone” are almost always pieces of man-made glass containing an abundance of tiny copper inclusions.
    [Show full text]
  • Tungsten and Gold Recovery from Alaskan Scheelite-Bearing Ores
    ¿I ri 9251 REPORT OF INVESTIGATIONS/1989 LIBRARY SPOKANE RESEARCH CENTER RECEIVED SEP5 1983 U.S. BUREAU OF MINES E 315 MONTGOMERY AVE SPOKANE, W A 99207 Tungsten and Gold Recovery From Alaskan Scheelite-Bearing Ores By J. N. Greaves, W. R. McDonald, and J. H. Maysilles M ission: As the Nation's principal conservation agency, the Department of the Interior has respon­ sibility for most of our nationally-owned public lands and natural and cultural resources. This includes fostering wise use of our land and water resources, protecting our fish and wildlife, pre­ serving the environmental and cultural values of our national parks and historical places, and pro­ viding for the enjoyment of life through outdoor recreation. The Department assesses our energy and mineral resources and works to assure that their development is in the best interests of all our people. The Department also promotes the goals of the Take Pride in America campaign by encouraging stewardship and citizen responsibil- ityforthe public lands and promoting citizen par­ ticipation in their care. The Department also has a major responsibility for American Indian reser­ vation communities and for people who live in Island Territories under U.S. Administration. Report of Investigations 9251 Tungsten and Gold Recovery From Alaskan Scheelite-Bearing Ores By J. N. Greaves, W. R. McDonald, and J. H. Maysilles UNITED STATES DEPARTMENT OF THE INTERIOR Manuel Lujan, Jr., Secretary BUREAU OF MINES T S Ary, Director Library of Congress Cataloging in Publication Data: Greaves, J. N. Tungsten and gold recovery from Alaskan scheelite-bearing ores. (Report of investigations / United States Department of the Interior, Bureau of Mines; 9251) Bibliography: p.
    [Show full text]
  • Lemhi County, Idaho
    DEPARTMENT OF THE INTERIOR UNITED STATES GEOLOGICAL SURVEY GEORGE OTIS SMITH, DIRECTOR BUIJLETIN 528 GEOLOGY AND ORE DEPOSITS 1 OF LEMHI COUNTY, IDAHO BY JOSEPH B. UMPLEBY WASHINGTON GOVERNMENT PRINTING OFFICE 1913 CONTENTS. Page. Outline of report.......................................................... 11 Introduction.............................................................. 15 Scope of report......................................................... 15 Field work and acknowledgments...................................... 15 Early work............................................................ 16 Geography. .........> ....................................................... 17 Situation and access.........................--.-----------.-..--...-.. 17 Climate, vegetation, and animal life....................----.-----.....- 19 Mining................................................................ 20 General conditions.......... 1..................................... 20 History..............................-..............-..........:... 20 Production.................................,.........'.............. 21 Physiography.............................................................. 22 Existing topography.................................................... 22 Physiographic development............................................. 23 General features...............................................'.... 23 Erosion surface.................................................... 25 Correlation............. 1..........................................
    [Show full text]
  • Myths and Realities in Artisanal Gold Mining Mercury Contamination
    MYTHS AND REALITIES IN ARTISANAL GOLD MINING MERCURY CONTAMINATION by GUSTAVO ANGELOCI SANTOS A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF APPLIED SCIENCE in THE FACULTY OF GRADUATE STUDIES (Mining Engineering) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) April 2013 © Gustavo Angeloci Santos 2013 ABSTRACT The world faces a major gold rush currently. Worldwide 15 million people work directly in artisanal gold mining in more than 55 countries. The usual method of extraction is amalgamation and cyanidation, or very commonly a combination of both. Significant amounts of contaminants are released to rivers and soil, generating environmental and health concerns. The majority of artisanal miners are involved in micro-mining, but it is believed that the majority of contamination comes from small to large artisanal operations. Larger operations involve less people, but process much more material, re- leasing much more contaminants as well. The present work explains how contamination is generated, through a com- prehensive analysis of the labor division in small-scale mining sites around the world, and also analyses aspects of different intervention approaches. Different approaches are taken by different groups working on the problem around the world. This work evaluates the most common kinds of interven- tion, with special attention to technical and legal aspects in trying to elimi- nate mercury use in gold extraction. The study is conducted by comparing different interventions strategies to evaluate the myths and realities from an engineering perspective. Special attention is paid to the evaluation of alterna- tives to amalgamation process for gold such as intensive cyanidation, borax direct smelting and chlorination.
    [Show full text]
  • COBALT GLASS AS a LAPIS LAZULI IMITATION by George Bosshart
    COBALT GLASS AS A LAPIS LAZULI IMITATION By George Bosshart A ~lecl<laceof round beads offered as "blue quartz from India" was analyzed by gemological and addition~~l advanced techniques. The violet-blue ornamental material, which resembled fine-q~ralitylapis lazuli, turned OLJ~LO be a nontransparent cobalt glass, unlil<e any glass observed before as a gem substit~zte.The characteristic color irregularities of lapis (whjtein blue) had been imjtated by white crystdlites of low- crjstobalite .ir~cludeclin the deep blue glass. The gemological world is accustomed to seeing gemstones from new localities, as well as new or improved synthetic crystals. With this in mind, it is not surprising that novel gem imitations are also encountered. One recent example is 'lopalitellla 400 500 600 700 convincing yet inexpensive plastic imitation of Wavelength A (nm) white opal manufactured in Japan. This article de- scribes another gem substitute that recently ap- Figure 1. Absorptio~ispectrum of a cobalt glass peared in the inarlzetplace. imitating lapis lazuli recorded ~hrougha chjp of Hearing of an "intense blue quartz from India1' approximately 2.44 inm thickness in the range of was intriguing enough to arouse the author's sus- 820 nm 10 300 nm, ot room temperature (Pye picion when a neclzlace of spherical opaque Ui7jcam SP8-100 Spectrophotometer). violet-blue 8-mm beads was submitted to the SSEF laboratory for identification. Because blue quartz in nature is normally gray-blue as a result of the refractive index of the tested material (1.508)does presence of Ti02(Deer et al.! 1975! p. 2071 or tour- not differ marlzedly from that of lapis (approxi- maline fibers (Stalder) 1967)! this particular iden- mately 1.50)/ its specific gravity of 2.453 is tification could be immediately rejected.
    [Show full text]
  • Mercury and Mercury Compounds
    United States Office of Air Quality EPA-454/R-97-012 Environmental Protection Planning And Standards Agency Research Triangle Park, NC 27711 December 1997 AIR EPA LOCATING AND ESTIMATING AIR EMISSIONS FROM SOURCES OF MERCURY AND MERCURY COMPOUNDS L & E EPA-454/R-97-012 Locating And Estimating Air Emissions From Sources of Mercury and Mercury Compounds Office of Air Quality Planning and Standards Office of Air and Radiation U.S. Environmental Protection Agency Research Triangle Park, NC 27711 December 1997 This report has been reviewed by the Office of Air Quality Planning and Standards, U.S. Environmental Protection Agency, and has been approved for publication. Mention of trade names and commercial products does not constitute endorsement or recommendation for use. EPA-454/R-97-012 TABLE OF CONTENTS Section Page EXECUTIVE SUMMARY ................................................ xi 1.0 PURPOSE OF DOCUMENT .............................................. 1-1 2.0 OVERVIEW OF DOCUMENT CONTENTS ................................. 2-1 3.0 BACKGROUND ........................................................ 3-1 3.1 NATURE OF THE POLLUTANT ..................................... 3-1 3.2 OVERVIEW OF PRODUCTION, USE, AND EMISSIONS ................. 3-1 3.2.1 Production .................................................. 3-1 3.2.2 End-Use .................................................... 3-3 3.2.3 Emissions ................................................... 3-6 4.0 EMISSIONS FROM MERCURY PRODUCTION ............................. 4-1 4.1 PRIMARY MERCURY
    [Show full text]