Sulfide ore flotation collector containing thiourea functional group

The chemical structure of thiourea collectors is:

where R1 is a hydrocarbon group or a substituted hydrocarbon group, and R2 is a hydrogen (H), hydrocarbon group or substituted hydrocarbon group.

Thiourea collectors can be divided into hydrocarbon thiourea, acylthiourea, hydrocarbon carbonylthiourea, hydrocarbonylthiourea and dithiourea.

Physicochemical properties

The four atoms in thiourea functional group   form a planar triangular structure, and C adopts sp2 hybridization with N, N, S forms large π bonds; the hydrogen atoms on the two nitrogen atoms in the molecule can activate the electrophilic substrate in the reaction system by forming double hydrogen bonds and improve their nucleophilicity; the sulfur atom and nitrogen atom in the molecule have free electron pairs, which can be used as electron donors to form synergistic coordination bonds, making thiourea a strong ligand with strong coordination ability; some bond lengths and bond angles of thiourea are between single bonds and double bonds, indicating that thiourea compounds have conjugation, and if the hydrogen atoms on them are replaced by suitable groups, the corresponding groups can extend the conjugated electron system and enhance their selective coordination of transition metals. The basic structure of thiourea determines its metal chelating properties, therefore, thiourea is commonly used to separate and enrich precious metals, and is widely used in hydrometallurgy and mineral processing.

Acylthiourea collectors include a series of monoacylthioureas and diacylthioureas, such as n-hexanoylthiourea, n-caprylyl thiourea, benzoylthiourea, succinicl dithiourea, adipyldithiourea, adipyldithiourea, terephthalicyldithiourea, etc. Oxycarbonylthiourea, which includes monoesterylthiourea and diesteryldithiourea, is widely used in the flotation recovery of soft metal sulfide minerals due to its selective chelation of transition metals.

Preparation method

The synthesis of thiourea collectors mainly uses the isothiocyanate method and the carbon disulfide method. The isothiocyanate method is to synthesize thiourea compounds from isothiocyanate and amines, and the reaction equation is as follows:

By changing the structure of the hydrocarbon group R, hydrocarbonyl thiourea, hydrocarbonyl thiourea, and hydrocarbonylthiourea can be prepared. The structure of the hydrocarbon group R is different, the reaction conditions of the synthesis intermediate N-isothiocyanate are different, and the reaction conditions of thiourea synthesis are also different.

Dithiourea can be synthesized by using bisisothiocyanate and amine as raw materials or isothiocyanate and diamine as raw materials.

The carbon disulfide method is to synthesize thiourea compounds with carbon disulfide and amine as raw materials, and the reaction equation is as follows:

Application

Thiourea collectors have chelating effect on copper, silver, gold and other metal ions, have strong capture ability, and have good selectivity, which can achieve copper-sulfur separation and recover precious metals under medium alkaline conditions. The capture capacity of thiourea collectors is equivalent to that of xanthate, stronger than thiourethane, and its selectivity is better than that of xanthate, which is suitable for flotation capture of copper minerals, zinc minerals activated by copper ions, nickel minerals, etc. In particular, hydrocarbonyl thiourea and hydrocarbonyl thiourea collectors are strong collectors in the range of pH value of 3~10, which can be mixed with flotation sulfides under acidic conditions, and can achieve selective flotation separation of copper minerals under medium alkaline conditions, reduce the amount of lime, and improve the comprehensive recovery rate of precious metals such as gold, silver and platinum.

Postscript

1. This article is excerpted from "Encyclopedia of China"

2. The thiourea products produced by Sinhon Chemical Technology Co., Ltd.  have high purity and good performance. It is the right choice to choose thiourea products produced by SINHON for mineral flotation.