Iron Sulfide Oxidation as Influenced by Calcium Carbonate Application

2003 ◽  
Vol 32 (3) ◽  
pp. 773-780 ◽  
Author(s):  
L. R. Hossner ◽  
J. J. Doolittle
Keyword(s):  
Calcium Carbonate ◽  
Iron Sulfide ◽  
Sulfide Oxidation

Pétrographie et minéralogie des halos d'altération autour du gisement de Cigar Lake et leurs relations avec les minéralisations

1993 ◽  
Vol 30 (4) ◽  
pp. 674-688 ◽  
Author(s):  
A. Pacquet ◽  
F. Weber
Keyword(s):  
Iron Sulfide ◽  
Sulfide Oxidation ◽  
Magnesium Content ◽  
Alteration Zone ◽  
Iron Hydroxides ◽  
Alteration Halo ◽  
Fracture Event ◽  
Iron Bearing ◽  
Uranium Complex

Around the Cigar Lake orebody, the present zoneography of alteration halos reflects several alteration episodes, some of which are anterior to and others coeval with the mineralizing events and have a regional extension. The basement retromorphism is characterized by crystallization of muscovite with a low iron and magnesium content and of trioctahedral ferromagnesian chlorites. The later regolith alteration, more obvious at the top of the basement, is marked by iron-bearing 1T kaolinite, by hematite, and by local crandallite–florencite and diaspore. In the Athabasca sandstones far from any mineralization, the diagenetic quartzification was followed by crystallization of aluminous 2M hydromuscovite, dickite, and crandallite–goyazite.In the main pod, the uraninite mineralization was dated 1341 ± 12 Ma. In the sandstones, it is surrounded by ferromagnesian chlorites with a variable sudoitic character. This proximal alteration halo grades into a more distal envelope, visible in the sandstone and in the basement, that is composed of magnesian sudoite and 3T hydromuscovite. During this mineralizing event, dravite crystallized in the form of urchin-like clusters in the basement and xenotime overgrowths, around altered zircon, and apatite formed in the sandstones.Around the main pod and in some perched orebodies, an alteration zone of vanadium-bearing ferrikaolinite and iron-bearing 3T hydromuscovite, crosscut by a later siderite, surrounds the pitchblende dated 323 ± 4 Ma. Coffinite and an aluminous hydromuscovite crystallized during a later fracture event. The aluminous hydromuscovite also appears, with a silica–carbon–uranium complex, in perched mineralizations. Kaolinization and iron-sulfide oxidation into iron hydroxides occurred in perched orebodies that were more exposed to meteoric alteration.

Iron sulfide oxidation and the chemistry of acid generation

1988 ◽  
Vol 11 (3) ◽  
pp. 289-295 ◽  
Author(s):  
Patrick J. Sullivan ◽  
Jennifer L. Yelton ◽  
K. J. Reddy
Keyword(s):  
Iron Sulfide ◽  
Sulfide Oxidation ◽  
Acid Generation

Pyrite and the Global Environment

Pyrite ◽  
2015 ◽  
Author(s):  
David Rickard
Keyword(s):  
Iron Sulfide ◽  
Sulfide Oxidation ◽  
Sulfate Reducing Bacteria ◽  
Sulfide Mineral ◽  
Sulfur Cycle ◽  
Sulfate Reducing ◽  
Global Dynamic ◽  
Sulfur Oxidizing ◽  
Life On Earth ◽  
Reducing Bacteria

The two basic processes concerning pyrite in the environment are the formation of pyrite, which usually involves reduction of sulfate to sulfide, and the destruction of pyrite, which usually involves oxidation of sulfide to sulfate. On an ideal planet these two processes might be exactly balanced. But pyrite is buried in sediments sometimes for hundreds of millions of years, and the sulfur in this buried pyrite is removed from the system, so the balance is disturbed. The lack of balance between sulfide oxidation and sulfate reduction powers a global dynamic cycle for sulfur. This would be complex enough if this were the whole story. However, as we have seen, both the reduction and oxidation arms of the global cycle are essentially biological—specifically microbiological—processes. This means that there is an intrinsic link between the sulfur cycle and life on Earth. In this chapter, we examine the central role that pyrite plays, and has played, in determining the surface environment of the planet. In doing so we reveal how pyrite, the humble iron sulfide mineral, is a key component of maintaining and developing life on Earth. In Chapter 4 we concluded that Mother Nature must be particularly fond of pyrite framboids: a thousand billion of these microscopic raspberry-like spheres are formed in sediments every second. If we translate this into sulfur production, some 60 million tons of sulfur is buried as pyrite in sediments each year. But this is only a fraction of the total amount of sulfide produced every year by sulfate-reducing bacteria. In 1982 the Danish geomicrobiologist Bo Barker Jørgensen discovered that as much as 90% of the sulfide produced by sulfate-reducing bacteria was rapidly reoxidized by sulfur-oxidizing microorganisms. Sulfate-reducing microorganisms actually produce about 300 million tons of sulfur each year, but about 240 million tons is reoxidized. The magnitude of the sulfide production by sulfate-reducing bacte­ria can be appreciated by comparison with the sulfur produced by volcanoes. As discussed in Chapter 5, it was previously supposed that all sulfur, and thus pyrite, had a volcanic origin. In fact volcanoes produce just 10 million tons of sulfur each year.

The causes and effects of aging in quick clays

1985 ◽  
Vol 22 (3) ◽  
pp. 335-346 ◽  
Author(s):  
Ghislain Lessard ◽  
James K. Mitchell
Keyword(s):  
Calcium Carbonate ◽  
Pore Water ◽  
Iron Sulfide ◽  
Carbonic Acid ◽  
Iron Hydroxide ◽  
Liquid Limit ◽  
Key Words Aging ◽  
Liquidity Index ◽  
Aging Phenomenon ◽  
Effects Of Aging

The physicochemical properties of a clay from La Baie, Quebec were found to be typical of Champlain quick clays: very low plasticity, liquidity index greater than 3, sensitivity greater than 500, and pH of about 9.5. The mineralogy is characterized by the abundance of primary or "rock flour" minerals such as feldspar, quartz, amphibole, and calcite, with illite as the principal clay mineral. The pore water chemistry consists predominantly of sodium bicarbonate. Low concentrations of sulfate, calcium, and magnesium and high alkalinity and pH are attributed, in part, to anaerobic sulfate-reduction processes taking place in situ.Quick clay samples stored in the laboratory showed signs of aging regardless of the storage procedure. The remoulded strength and the liquid limit increased with time, whereas the sensitivity, the liquidity index, and the pH decreased. The water content, plastic limit, and undisturbed strength remained practically unchanged. The pore water concentrations of calcium, magnesium, and sulfate increased by severalfold.The aging phenomenon is attributed, for the most part, to the oxidation of iron sulfide, which results in the formation of iron hydroxide and sulfuric acid. The production of acid causes the dissolution of calcium carbonate, which increases the concentration of divalent cation in the clay, thereby reducing interparticle repulsion and increasing the remoulded strength. The oxidation of organic matter, resulting in the formation of carbonic acid, also contributes to the aging by its effect on the solubility of calcium carbonate. Key words: aging, chemical reactions, physicochemical phenomena, sensitivity, time effects.

The Importance of Microbial Iron Sulfide Oxidation for Nitrate Depletion in Anoxic Danish Sediments

2014 ◽  
Vol 20 (4) ◽  
pp. 419-435 ◽  
Author(s):  
Sarka Vaclavkova ◽  
Christian Juncher Jørgensen ◽  
Ole Stig Jacobsen ◽  
Jens Aamand ◽  
Bo Elberling
Keyword(s):  
Iron Sulfide ◽  
Sulfide Oxidation ◽  
Nitrate Depletion

Rates of Iron Sulfide Oxidation in Coal Spoil Suspensions

1985 ◽  
Vol 14 (1) ◽  
pp. 91-94 ◽  
Author(s):  
V. P. Evangelou ◽  
J. H. Grove ◽  
F. D. Rawlings
Keyword(s):  
Iron Sulfide ◽  
Sulfide Oxidation
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