Minerals
The forms in which metals are found in the crust of the earth and as seabed deposits depend on their reactivity with their environment, particularly with oxygen, sulphur and carbon dioxide. Gold and the platinum are found principally in the native and metallic form. Silver, copper and mercury are found native, as well as in the form of sulphides, carbonates, and chlorides. The more reactive metals are al ways in compound form, such as the oxides and sulphides of iron and the oxides and silicates of aluminium and beryllium. The naturally occurring compounds are known as minerals, most of which have been given names according to their composition ( e. g. galena-lead sulphide, PbS; sphalerite-zinc sulphide, ZnS; cassiterite-tin oxide, Sn02).
Minerals by definition are natural inorganic substances possessing definite chemical compositions and atomic structures. Some flexibility, however, is allowed in this definition. Many minerals exhibit isomor’phism, where substitution of atoms within the crystal structure by similar atoms takes place without affecting the atomic structure. The mineral olivine, for example, has the chemical composition (Mg, Fe)iSi04, but the ratio of Mg atoms to Fe atoms varies in different olivines. The total number of Mg and ,Fe atoms in all olivines, however, has the same ratio to that of the Si and O atoms. Minerals can also exhibit polymorphism, different minerals having the same chemical composition, but markedly different physical properties due to a difference in atomic structure. Thus the two minerals graphite and diamond have exactly the same composition, being composed entirely of carbon atoms, but have widely different properties due to the arrangement of the carbon atoms within the crystal lattice. The term “mineral” is often used in a much more extended sense to include anything of economic value which is extracted from the earth. Thus coal, chalk, clay and granite do not come within the definition of a mineral, although details of their production are usually included in national figures for mineral production. Such minerals are, in fact, rocks, which are not homogeneous in chemical and physical composition, as are minerals, but generally consist of a variety of minerals and form large parts of the earth’s crust. Granite, for instance, which is the most abundant igneous rock, i.e. a rock formed by cooling of molten material, or magma within the earth’s crust, is composed of three main mineral constituents, feldspar, quartz and mica. These three homogeneous mineral components occur in varying proportions in different granites, and even in different parts of the same granite mass.
Metallic Ores
An ore can be described briefly as an accumulation of mineral in sufficient quantity as to be capable of economic ext.raction. This establishes the market price of the metal as a critical criterion in the definition, and this will vary according to the commercial demands. With the passage of time and depletion of richer or more readily accessible material, a mineral deposit may be updated to an ore. Improvement in metallurgical extraction and the introduction of new methods also become factors in making available deposits hitherto regarded as uneconomic. Thus the introduction of the flotation process in mineral .processing permitted the extraction of copper from material containing less than 0. 5 % of the metal and formerly regarded as waste, Similarly the introduction of solvent extraction has enabled Nchanga Consolidated Copper Mines in Zambia to treat 9 million tonnes per year of flotation tailings, produ.cing 80,000 tqnnes of finished copper from what was previously regarded as waste material.
Ores are frequently classed according to the nature of the valuable mineral. Thus in native ores the metal is presented in the elementary form; sulphide ores contain the metal in the form of a sulphide, and in oxidised ores the valuable mineral may be present as oxide, sulphate, silicate, carbonate, or some hydrated from of these. Complex ores are those containing profitable amounts of more than one valuable mineral. Metallic minerals are often found in certain associations, within which they may occur as mixtures of a wide range of particle sizes or as single-phase solid solutions or compounds. Galena and sphalerite, for example, commonly associate, as do copper sulphide minerals .and sphalerite to a lesser extent. Pyrite (FeSz) is very often associated with these minerals.
Ores are also classified by the nature of their gangues, such as calcareous or basic ( lime rich), or siliceous, or acidic (silica rich) .
T·he minimum metal content required for a deposit to qualify as an ore varies from metal to metal. Many nonferrous ores contain, as mined, as little as 1 % metal, and often much less. Gold may be recovered profitahly in ores containing only 5 parts per million (ppm) of the metal, whereas iron ores containing less than about 20 % metal are regarded as low grade.
There are many plants_ where minerals are recovered in secondary circuits, treating tailings, where the feed grades are much low·er than would be economic on a mined ore. Typical ore grades for tungstel’) ores are in the range of 0. 5 ½ ~ 1. 5 ½ WQ3 , but the Climax Molybdenum plant in the United States treats 45, ·ooo tonnes per day of tailings, containing less than 0.· 1 % W03 , and is one of the two major producers of tungsten concentrate in the United States.
Non-metallic Ores
Ores of.economic value can be classed as metallic o.r non-metallic, according to the use of the mineral. Certain minerals may be mined and processed for more than one purpose. In one category the mineral may be a metal ore, i.e. when it is used to prepare the metal. as when bauxite (hydrated aluminium oxide). is used to make aluminium. The alternative is for the compoup.d to be classified as a non-metallic ore, i. e. when bauxite or natural aluminium oxi’de is used to make material for refractory bricks or abrasives.
Many non-metallic ore minerals associate with metallic ore minerals and are mined and processed together, e. g. galena, the main source of lead often associates with fluorite (CaF2 ) and barytes (BaS04 ), both important non-metallic minerals.
Attractive section of content. I just stumbled upon your blog and in accession capital
to assert that I get in fact enjoyed account your blog posts.
Any way I will be subscribing to your feeds and even I
achievement you access consistently rapidly.
Hey very nice blog!
Thanks for your personal marvelous posting!
I quite enjoyed reading it, you’re a great author.I
will remember to bookmark your blog and will often come back in the future.
I want to encourage you to ultimately continue your great writing, have a nice weekend!
whoah this weblog is excellent i like studying your articles.
Stay up the good work! You know, lots of individuals are
looking around for this information, you can aid them greatly.
Hi! Do you use Twitter? I’d like to follow you if that would be ok.
I’m undoubtedly enjoying your blog and look
forward to new updates.
Awesome site you have here but I was curious
about if you knew of any user discussion forums that cover the same topics talked about in this article?
I’d really love to be a part of group where I can get comments from other experienced people that share the same
interest. If you have any recommendations, please
let me know. Appreciate it!
Hey There. I discovered your weblog the usage of msn. That is a very neatly written article.
I’ll be sure to bookmark it and come back to read more of your
helpful information. Thanks for the post. I’ll definitely comeback.
Attractive section of content. I just stumbled
upon your web site and in accession capital to assert that I get
actually enjoyed account your blog posts. Any way I’ll be subscribing to your
feeds and even I achievement you access consistently quickly.
First off I want to say great blog! I had a quick question in which I’d like to ask
if you do not mind. I was curious to find out how you center yourself and
clear your mind prior to writing. I’ve had a difficult time clearing my thoughts in getting my thoughts out.
I do enjoy writing however it just seems like the first 10 to 15 minutes are usually wasted just trying to figure out how to begin. Any suggestions or tips?
Kudos!
Hello! I know this is somewhat off topic but I was wondering if you knew where I could find a captcha plugin for
my comment form? I’m using the same blog platform as yours and I’m having problems finding
one? Thanks a lot!
My spouse and I stumbled over here coming from
a different page and thought I might check things out.
I like what I see so now i am following you. Look forward to exploring your web page again.
Remarkable! Its in fact remarkable article, I have got much clear
idea regarding from this post.
I don’t know whether it’s just me or if everybody else experiencing problems with your blog.
It appears like some of the written text on your content are running
off the screen. Can someone else please comment and let me know if this is happening to them as
well? This could be a problem with my web browser because
I’ve had this happen before. Kudos
I use the microsoft edge explorer, but I do not have the same problem as you.
would you like to tell me which browser you use?
It’s the best time to make some plans for the long run and it is time to be happy.
I’ve learn this post and if I could I desire to counsel you some attention-grabbing things or advice.
Maybe you can write next articles referring to this article.
I wish to read even more things about it!
excellent publish, very informative. I’m wondering why the opposite experts of this sector don’t notice this.
You should continue your writing. I am confident, you’ve a
great readers’ base already!
Also visit my webpage
We absolutely love your blog and find the majority
of your post’s to be just what I’m looking for. Do you offer guest writers to write content to suit your needs?
I wouldn’t mind publishing a post or elaborating on most of the subjects
you write regarding here. Again, awesome weblog!
My site ::
It’s going to be ending of mine day, but before
finish I am reading this impressive post to increase my know-how.
Here is my website: best kratom (Mike)
I do not even understand how I stopped up here, but I believed
this submit was once great. I don’t recognise who you’re however definitely
you’re going to a well-known blogger when you are not already.
Cheers!
Here is my web-site; best cbd gummies for pain
I like the helpful information you provide in your articles.
I’ll bookmark your weblog and check again here frequently.
I am quite certain I will learn many new stuff right here!
Best of luck for the next!
I always used to study article in news papers but now as I am a user of
web therefore from now I am using net for articles or reviews, thanks to web.
I’m extremely impressed along with your writing abilities and also with the structure on your
weblog. Is this a paid theme or did you customize
it yourself? Anyway stay up the excellent quality writing,
it’s rare to look a great blog like this one today..
bookmarked!!, I like your web site!
What’s up colleagues, good post and pleasant urging commented at this place,
I am actually enjoying by these.
Hey just wanted to give you a quick heads up. The words in your content seem
to be running off the screen in Firefox. I’m not sure if this is
a formatting issue or something to do with web browser compatibility but
I thought I’d post to let you know. The layout look great though!
Hope you get the issue fixed soon. Cheers
Good info. Lucky me I discovered your blog by chance (stumbleupon).
I have saved as a favorite for later!
Woah! I’m really enjoying the template/theme of this blog. It’s simple, yet effective. A lot of times it’s very hard to get that “perfect balance” between superb usability and visual appearance. I must say that you’ve done a superb job with this. Additionally, the blog loads very quick for me on Firefox. Superb Blog!|