How is uranium 235 collected?

Answer 1

Uranium is collected via mining. As with other types of hard rock mining there are several methods of extraction. The main methods of mining are open pit mining and in situ leaching (ISL).

Open pit

In open pit mining, overburden is removed by drilling and blasting to expose the ore body which is mined by blasting and excavation via loaders and dump trucks. Workers spend much time in enclosed cabins thus limiting exposure. Water is extensively used to suppress airborne dust levels.

Underground uranium mining

If the uranium is too far below the surface for open pit mining, an underground mine might be used with tunnels and shafts dug to access and remove uranium ore. There is less waste material removed from underground mines than open pit mines, however this type of mining exposes underground workers to the highest levels of radon gas.

Heap leaching

Waste rock is produced during open pit mining when overburden is removed, and during underground mining when driving tunnels through non-ore zones. In some cases uranium has been removed from this low-grade ore by heap leaching. This may be done if the uranium contents is too low for the ore to be economically processed in a uranium mill. The leaching liquid (often sulfuric acid) is introduced on the top of the pile and percolates down until it reaches a liner below the pile, where it is caught and pumped to a processing plant. Due to the potential for extreme damage to the surrounding environment, this practice is no longer in use.

In-situ leaching

In-situ leaching (ISL), sometimes referred to as in-situ recovery (ISR) or solution mining, is performed by pumping liquids (weak acid or weak alkaline depending on the calcium concentration in the ore) down through injection wells placed on one side of the deposit of uranium, through the deposit, and up through recovery wells on the opposing side of the deposit - recovering ore by leaching. ISL is also used on other types of metal extraction such as copper. ISL is often cost-effective because it avoids excavation costs, and may be implemented more quickly than conventional mining. However, it is not suitable to all uranium deposits, as the host rock must be permeable to the liquids (as is often the case in sandstone).

Recovery from seawater

The uranium concentration of sea water is low, approximately 3.3 mg per cubic meter of seawater (3.3 ppb). But the quantity of this resource is gigantic and some scientists believe this resource is practically limitless with respect to world-wide demand. That is to say, if even a portion of the uranium in seawater could be used the entire world's nuclear power generation fuel could be provided over a long time period. Some anti-nuclear proponents claim this statistic is exaggerated. Although research and development for recovery of this low-concentration element by inorganic adsorbents such as titanium oxide compounds, has occurred since the 1960s in the United Kingdom, France, Germany, and Japan, this research was halted due to low recovery efficiency.

Answer 2

The long half-life of the isotope uranium-238 (4.51 × 109 years) makes it well-suited for long term storage in a shielded bunker. According to an interview from Scientific American, one Russian facility had been storing samples of enriched (weapons grade) uranium in a broom closet prior to the improvement project; another had been keeping track of its stock of nuclear warheads using index cards kept in a shoe box.

About 95 percent of the depleted uranium produced is stored as uranium hexafluoride, a crystalline solid, (D)UF6, in steel cylinders in open air storage yards close to enrichment plants. Each cylinder holds up to 12.7 tonnes (or 14 US tons) of UF6. In the U.S. 560,000 tonnes of depleted UF6 had accumulated by 1993. In 2008, 686,500 tonnes in 57,122 storage cylinders were located near Portsmouth, Ohio and Paducah, Kentucky.

Answer 3

The storing of uranium depends on:

- the enrichment in uranium-235

- irradiated uranium or not

- physical form: solid, liquid or gaseous compounds

- chemical form: metal, uranium hexafluoride, uranyl nitrate solution, uranium dioxide, etc.

- quantity

etc.

To problem is complex, difficult to explain in brief here; we can use stainless steel containers, glass bottles, tanks of glass fibers reinforced polythene or polystyrene, metallic tanks, etc. - after the situation. Of course the storage area will be under severe surveillance.

Answer 4

The isotope uranium-235 is obtained by enriching natural uranium using different techniques of isotopes separation (thermal diffusion, gaseous diffusion, centrifuging, lasers, ion exchange, nozzle, etc.).

Answer 5

It is not very reactive until it has been used in a reactor.

Answer 6

Each country has very severe regulations for the control of uranium use, stocks, production and trade.

Also generally applied are the IAEA safeguards.

Answer 7

Anywhere, but under controlled conditions.

Answer 8

Uranium is extracted from mines.