Heavy liquid
As heavy liquid , is known especially in the mineralogy , a liquid with high density . They are used in mineralogy to determine density with the levitation method and to separate mineral mixtures.
Gravity separation (sink-float treatment)
Heavy liquids are used in mineralogy to separate minerals by gravity . For this purpose, the heterogeneous material to be separated is first carefully crushed. It is important to avoid breaking the individual mineral components themselves. The crushed material is now placed in the heavy liquid. The minerals settle at the bottom of the container with a density that is higher than that of the liquid used, while the lighter components float up. Only the minerals, whose density corresponds to that of the liquid, remain in suspension. A separation into two or three fractions is therefore quite easy. By changing the density of the heavy liquid, for example by mixing it with another liquid, a different density can be set and the fractions obtained can optionally be further fractionated.
toxicity
The classic heavy liquids used in mineralogy, such as 1,1,2,2-tetrabromoethane ( Muthmann's liquid ), potassium tetraiodomercurate (II) ( Thoulets solution ), bromoform and methylene iodide , are extremely toxic. In principle, toxic liquids can be largely dispensed with today, since a density range of 2.5–3.1 g · cm −3 with a low viscosity can be set with non-toxic aqueous sodium poly tungstate solutions . By adding extremely fine tungsten carbide powder, the density can even be increased to 4.6 g · cm −3 .
Selection of classic heavy liquids with a density> 2.0 g · cm −3
| designation | Density in g cm −3 |
|---|---|
| 1,2-dibromoethane | 2.056 |
| cis-1,2-dibromoethene | 2.246 |
| trans-1,2-dibromoethene | 2.231 |
| Dibromomethane | 2.453 |
| Bromal | 2,550 |
| Bromoform | 2,890 |
| 1,1,2,2-tetrabromoethane (Muthmann's liquid) | 2.963 |
| Sodium poly tungstate | 3,100 |
| Thoulets solution | 3.196 |
| Diiodomethane | 3.233 |
| Indium (III) iodide | 3.40 |
| Barium mercury iodide | 3.57 |
| Clerici solution | 4.25 |
literature
- W. Schnitzer: On the problem of heavy mineral analysis using the example of Triassic sedimentary rocks. In: International Journal of Earth Sciences. 72/1983, pp. 67-75, doi : 10.1007 / BF01765900 .
- W. Boenigk: Heavy Mineral Analysis. Enke, Stuttgart 1983, ISBN 3-432-92931-5 , pp. 6-15.
- P. Ney: Rock preparation in the laboratory. Enke, Stuttgart 1986, ISBN 3-432-95971-0 , pp. 92-113.
Web links
Individual evidence
- ↑ J. Callahan: A non-toxic heavy liquid and inexpensive filters for separation of mineral grains. In: Journal of Sedimentary Petrology. 57/1987, pp. 765-766.
- ↑ Entry on heavy liquids. In: Römpp Online . Georg Thieme Verlag, accessed on June 13, 2014.
- ↑ sensotech.com: Concentration and density measurement. - Density of various liquids, accessed July 4, 2007.
- ↑ WA Herrmann, Norbert Auner, Uwe Klingebiel: Synthetic Methods of Organometallic and Inorganic Chemistry, Volume 2, 1996 Volume 2: Groups 1,2, 13 and 14 . Georg Thieme Verlag, 2014, ISBN 3-13-179421-6 ( limited preview in the Google book search).