Fluoroammonium technology of technogenic raw materials processing

During ore dressing and processing besides end product shipping there also takes place great production of wastes. So, in non-ferrous metallurgy for 1 ton of metal there is up to 12 tons of slag; because of imperfections of ore dressing and processing techniques a lot of important components are lost with slag. Content of various important components in metallurgic slag usually exceeds their content in ores, but complex processing technology does not exist yet.

The basis of metallurgic slag consist silicon oxide and iron oxide. Silicon oxide is a hardly opened constituent of slag, and the presence of great amount of cheap iron oxide can make the whole process unprofitable. Thus, before extracting important components out of slag, two basic problems have to be solved:

separation of silicon oxide;

separation of iron oxide.

The difficulty of metallurgic clinkers processing lies in their silicate nature. Clinker is a mixture of vitrified (melted in silicon oxide) metal oxides. The most convenient reagent for silicate minerals opening are ammonium fluorides. Possibility of ammonium fluoride regeneration allows establishing of the continuous desiliconizing cycle and extracting quartz constituent of slag in the form of fine-dyspersated silicon oxide of “white black” sort. Below there is given a cycle fluoroammonium desiliconization and ammonium fluoride regeneration with precipitation of silicon oxide in the form of the so-called “white black”.

After filtrational separation of silicon oxide there remains ammonium fluoride solution, which goes to desiliconization of new part of slag. As the next step in the research of techniques of metallurgic slag opening there was developed method of ammonium-chloride deferrization. As it was stated above, the presence of great amount of cheap iron oxide can make the whole process of important components extraction out of clinkers unprofitable. Here appeared a problem to find the technique which similarly to the desiliconization technique, described above, will let to regenerate basic reagent. This problem was solved by using ammonium chloride as deferrizing reagent.

As in the case of desiliconization the use of ammonium salt allows establishing regeneration cycle of basic reagent, i.e. ammonium chloride.

From in that way separated iron trichloride there can be regenerated ammonium chloride according to the reaction:

2FeCl3 + 6NH4OH → Fe2O3 + 6NH4Cl + 3H2O

The cycle of interaction between iron oxide and ammonium chloride, sublimation and sublimation separation of iron trichloride, regeneration of ammonium chloride and iron extraction out of system in the form of hydroxide are shown on the scheme.

In the result there was developed a sequence of operations that allows consequent desiliconization and deferrization of metallurgic slag. Silicon oxide is extracted out of slag in the form of ammonium hexafluosilicate, and iron oxide ‛ in the form iron trichloride.

Further processing of opened and enriched slag can be easily conducted by pyro- and hydrometallurgical techniques.