The occurrence of elements in ore and mineral processing products is one of the basic tasks of process mineralogy research. The form of the element in the ore is related to its own crystal chemistry and the physical and chemical conditions at which it is formed. The state of occurrence of an element has two meanings: the occurrence of the element and the state of the element. The occurrence of elements is the distribution of beneficial and harmful elements in ore or mineral processing products. The state refers to the form in which the element exists in the ore. Through the study of the state of occurrence of elements, it is important to find out the existence form and distribution law of elements in ore, which is of great significance to the selection and optimization of ore processing. The occurrence or existence of elements in ore is a product of geological processes. It reflects the history of deposit formation. It is closely related to basic geology such as geochemistry, crystal chemistry, mineralogy, crystallography and mineral deposits. The study of the occurrence state of elements is not only an important basis for geological personnel to study the geochemical law of elements, the physicochemical conditions of mineralization and the genesis of mineral deposits, but also the scientific basis for the research process of mineral processing technology researchers to evaluate the process and evaluate the quality of mineral processing products. The availability of valuable elements in the ore depends not only on the content of the elements in the ore, but also on the state of occurrence of the elements.

1 The state of occurrence of elements in ore

The form of production of an element in ore is related to its own crystal chemistry and the physical and chemical conditions of its formation. The state of occurrence of an element in ore can be divided into three main forms of output, namely, independent mineral forms and classes. The same form and adsorption form.

A independent mineral

When an element is present as a separate mineral, it constitutes one of the major and stable constituents of the mineral and occupies a specific location in the mineral lattice. The separate copper minerals chalcopyrite, chalcocite, cuprite, black copper, iron ore Akagane, malachite, azurite, copper phosphate and the like.

B type

The isomorphism is a more common form of occurrence of minerals in minerals. It refers to the phenomenon in which similar particles in the mineral lattice replace each other without changing the mineral structure. The elements produced in the form of isomorphism are different from the forms of independent minerals, which are usually not the main and stable constituents in the mineral lattice, but because of their crystallization chemistry and the crystallization chemistry of a major element in the mineral. Similar in nature, under certain conditions, enter the mineral lattice in the form of minor or trace elements. These elements do not change the crystal structure of the mineral after entering the mineral lattice.

If the mineral particles to each other in any proportions alternative unlimited Alternatively, called complete isomorphous. For example, crystal ferberite Mn2 + Fe2 + is an alternative number, it can vary from zero up to 100%, i.e. finally to pure MnW04, i.e. wolframite ore. The pure components at both ends are called end minerals, such as tungsten iron ore and tungsten manganese ore.

If the mutually replaced particles are confined to a limited range, they are called incompletely homogeneous images. For example, potassium feldspar K [AISi308] K + may be partially replace Na +, sodium feldspar Na [AISi308] may also be part of Na + K + is replaced. Again, in the sphalerite ZnS, there may replace part of the Zn2 Fe2 + +, but alternatively no more than about 45% (number of molecules). Therefore, the potassium-sodium feldspar series and the sphalerite-iron-sphale zinc series are all incompletely similar.

In addition, some rare elements with low abundance in the mantle are often substituted into the crystal lattice of other compounds in the form of isomorphism, forming incomplete isomorphisms, and their substitutions are very small. . This trace element replaces the main elements in the crystal with incomplete isomorphism, and is called intrinsic isomorphism in geochemistry; these alternative elements are often referred to as isomorphic impurities.

In the isomorphic substitution, the secondary component is often referred to as a homogeneous homologue. When the mutually exchanged particle prices are the same, they are called equivalent isomorphisms. For example, the aforementioned wolframite (Mn2+ and Fe2+ are substituted for each other) and the potassium-sodium feldspar series (K+ and Na+ are substituted for each other). If the replacement particle price is different, it is called the isomorphism. For example, neonite has an alternative relationship between Ca2+ and Na+ and Fe2+ and Fe3+ in (Na,Ca)(Fe3+,Fe2+)[Si206]. Any isomorphic homomorphism of the isomorphous crystals must be compensated by electricity price to maintain the balance of electricity prices. For example, in a neonite, one Fe2+ band replaces one Fe3+, and one Ca2+ replaces one Na+.

Scattered element itself does not form independent minerals, can only isomorphous mixed substances are dispersed in other minerals such as sphalerite of gallium, rhenium molybdenite, pyrite and other cobalt, as these The element content is usually very small and thus generally does not appear in the chemical formula. Usually these scattered elements selected from the first support and then the metallurgical mineral recovered.

C adsorption form

The element produced in the form of adsorption refers to the element being adsorbed in a certain mineral, and is classified into physical adsorption, chemical adsorption and exchange adsorption according to the nature of its adsorption. The element produced in the form of adsorption may be a simple cation, an anion or a colloidal particle, and the carrier mineral is mainly related to a clay mineral and a colloidal mineral such as iron oxide or manganese oxide. Because these minerals often have a charge on their surface, they tend to adsorb other particles. For example: The ion-adsorbed rare earth deposits in South China are characterized by the fact that rare earth elements are adsorbed by clay minerals such as kaolinite and kaolinite in a simple cation form; in iron cap type gold ore, limonite Fe203·nH20 is positive. Colloids, the surface of which tends to adsorb negatively charged gold colloidal particles [mAu°+nAu(0H)3+Au(0H)4].

2 Research methods for the existence of elements

Although there are many research methods for the state of element occurrence, the choice of research methods mainly depends on the nature of raw materials. The most commonly used ones are single mineral separation method, selective dissolution method, X-ray diffraction method, mineral microbeam analysis method, differential thermal analysis. Law, mathematical statistics and electrodialysis. The first five methods have been introduced before, and will not be described here. The following mainly introduces mathematical statistics and electrodialysis.

A mathematical statistics

Mathematical statistics is to synthesize, sort, and calculate the chemical analysis data of a large number of samples by mathematical statistics to obtain relevant data, and to understand the correlation of the elements according to the statistical data. Commonly used mathematical statistics methods are:

(1) One-way linear regression analysis correlation coefficient method.

(2) Mean and mean square error method. This is to use the relationship between the two elements in the ore, the degree of dispersion, and the coefficient of variation to determine the existence or occurrence of an element.

B Electrodialysis

The electrodialysis method is mainly used to examine some of the colloidal formations in the colloidal ore or ore, and to study whether there are elements in the form of adsorption. These elements are not the main elements that make up the basic components of the mineral, but are adsorbed by colloidal minerals with opposite charges to the element. The electrodialyzer consists of three chambers separated by a semi-permeable membrane (usually a sheepskin membrane). Figure 1 shows a schematic diagram of a Burwell-type electrodialysis unit. The left and right chambers are respectively equipped with DC positive and negative electrodes, and the middle chamber is filled with a suspension of ore powder and water, and is continuously stirred. The upper and lower portions of the two side chambers each have a small round hole, the upper hole is a water supply hole, and is connected to the bottle filled with distilled water; the lower hole is a drainage hole, and the drainage speed can be adjusted through the two-way valve. A siphon is placed in the two side chambers to ensure that the electrodes have a fixed level of liquid level. The electrodes are connected to an adjustable DC power supply. Under the action of DC electric field, if the mineral suspension has the adsorption state of ions (adsorbed on the surface of the colloidal mineral point), the adsorbed ions enter the solution due to the potential difference, and the opposite charges are transmitted through the semi-permeable membrane. The electrode chamber diffuses, the cations migrate to the cathode chamber, the anions migrate to the anode chamber, and accumulate around the platinum mesh electrode (the semipermeable membrane has small capillary pores that allow only ions to pass through without allowing colloidal minerals to pass). The higher the ion content of the solution in the electrode chamber (cathode chamber and anode chamber) after electrodialysis, the greater the amount of adsorbed ions.

Circulating liquid

Figure 1 Scheffer diagram of the Burwell-type electrodialysis machine

1 one electric room; 2 one middle room; 3 one siphon; 4 one cooler; 5 one film; 6 one electrode; 7 one input liquid pipe; 8 one rubber plug; 9 one water plug;

C element balance allocation calculation

The elemental equilibrium distribution calculation is to analyze the proportion of the target element in the minerals of the ore. It must be carried out in detail on the basis of the study of the ore material composition, especially the state of occurrence of the elements. On the basis of the study of the state of occurrence of elements, according to the results of mineral quantitative research and the determination of the content of elements in different minerals, the composition of each mineral in the ore can be calculated, that is, quantitative description of the state of occurrence of the element . Through the calculation results of elemental allocation, we can understand the distribution law of valuable elements and harmful elements in ore, and provide scientific basis for selecting process conditions and optimizing process indicators.

To the memory state D gold silver and gold lead speech Ore case study

Microscopic observation and scanning electron microscopy X-ray energy spectroscopy show that part of the gold in the ore is in the form of silver gold ore, gold and silver ore, but a large part is sodium cyanide solution or 8% I2 + 15%. The NH4I solution is also incapable of gold, which may be in the form of microscopic gold and submicroscopic gold. In order to ascertain the distribution of gold in the ore, the main minerals in the ore are separated and enriched, and the enriched pyrite concentrate, galena concentrate, sphalerite concentrate, and yellow containing poisonous sand are obtained. Iron ore concentrate. The content of the main minerals in these enriched concentrates was first determined, and then the gold was leached by agitation of 0.5% NaCN solution at room temperature for 24 hours, and the gold content in the residue was measured. Then, the content of gold in pyrite, galena, sphalerite and gangue minerals is obtained by solving the simultaneous equation method. The calculation results of gold content in the main minerals are shown in Table 3.

Note: P-pyrite contains gold (g/t); A-toxic sand contains gold (g/t); G-side lead ore contains gold (g/t); S-one zinc ore contains gold (g/t) ); X a gangue mineral contains gold (g / t).

Table 4 shows the equilibrium distribution of gold in various minerals.

Table 4 Balanced distribution of gold in ore

1 The gold content of gold minerals is the difference between the total gold content in the ore and the gold content of other minerals.

It can be seen from Table 4 that after the effect of bare gold is removed as much as possible under normal grinding fineness conditions, 77.39% of the gold in the ore is distributed in pyrite and arsenopyrite. Under normal conditions, this part Gold is difficult to leach with NaCN and I2+ KI solutions, possibly in the form of microscopic gold and submicroscopic gold. The gold in the galena, sphalerite and gangue minerals only accounted for 4.35%. In addition, 18.26% of the gold is in the form of gold and silver or silver and gold, which can be recovered by mineral processing or metallurgical treatment.

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