The production of colored sand and colored marble chips is a profitable and promising separate type of business or an additional direction in the activities of an existing production enterprise. Colored quartz and marble chips, colored sand have various fields of application. They are used for decorative landscaping (decorating pools, fountains, flower beds, etc.), for applying road markings and anti-slip coatings, for removing frost on dangerous sections of the roadway, etc. Crumb of various colors made of marble, quartz and sand has several advantages. It has chemical resistance to various reagents, water resistance, durability, frost resistance. Recently, polymer floor coverings, the main component of which is colored quartz sand, are becoming increasingly popular. Such coatings are used both in warehouse and industrial premises, as well as in shopping malls, night clubs and other public institutions. They not only increase the service life of the flooring, but also protect it from the effects of various chemicals. Another application of colored sand is the decoration of internal and external sections of residential and industrial premises. The colored quartz sand used for wall decoration hides all the roughnesses and minor imperfections of the surface.
Colored sands can also be applied to roofing materials, which allows you to give them, in addition to the rough, pleasant to the touch and appearance of the textured surface, almost any color scheme. Colored sand is used together with roofing materials such as concrete tiles, bitumen-based roofing materials, etc. Since almost all roofing materials are designed for a long time of use, the colored sand used with them must also have a high degree of color fastness. tones. This indicator depends not only on the pigments, but also on the binder with which the pigment is fixed on the grains of sand. However, sand can have a color (greenish, red, brown, yellow) and without the addition of dyes.
Sand can be of various types. It may be dominated by quartz, mica, volcanic glass or feldspar. For the production of colored sand, as a rule, pure quartz sand of high quality is used. Sometimes ordinary river sand with a suitable grain size is also used. The disadvantage of river sand in comparison with pure quartz sand is that the first contains iron oxides more or less than necessary, as a result of which its grains of sand can acquire a reddish hue after firing, which negatively affects the final color tone when mixing sand of different shades. Experts also advise against the use of sands, which contain a noticeable proportion of minerals with a carbonate content (for example, lime spar or dolomite), since at high temperatures at which firing is carried out, they decompose into calcium and magnesium oxides and carbon dioxide. When choosing raw materials, the size of grains of sand is of great importance, which is determined depending on the purpose of the finished product. This parameter is very important, since it directly affects the consumer properties of products. For example, to ensure a good fixation of the grains of sand in the base, which can be a bitumen substrate or cement slurry, they should be immersed in the base to a certain depth - not too deep to maintain the color effect, and not too high so that the sand coating does not wash off with roof surface. Sand with too large particles can sink into the base only on a small part of its volume, because of which it will be too loosely bound to it. Experts consider the optimal raw material for the manufacture of colored sand in most areas of its application sand with a grain size of sand from 0.5 to 1.2 mm. Moreover, their shape does not matter much.
The second important component of colored sand is binders. There are a large number of such substances, but inorganic binders are considered the most optimal option among them (primarily, for reasons of resistance to atmospheric precipitation and production costs). In particular, in most cases, sodium silicate or aluminum monophosphate is used. At high temperatures, these substances form highly polymer glassy compounds into which the pigment is immersed. Dyes are fixed on the surface of the sand and at the same time are resistant to moisture and temperature extremes. These parameters are affected by the temperature and duration of firing, as well as the amount of binder used (usually 2-3% of the binder of the total mass of sand).
The technology for the production of colored sands consists of three main stages: mixing, firing, cooling and shipping. To mix the main components - sand, pigment and a binder, a mixer with a capacity of 150 to 250 liters is used. Such mixers are also used in the production of concrete. The required amount of sand is loaded into the mixer, then after it is included in the tank, a portion of pigment and a measured amount of binder are added (the order of loading can vary). All these components are mixed for 3-5 minutes. It is recommended to add 1-1.5 liters of water per 100 kg of sand to air-dry sand. This allows you to achieve a uniform distribution of pigment on the surface of grains of sand.
To obtain reliable fixation of the pigment on the grains of sand, inorganic binders are fired at a temperature of 600 to 1000 ° C. Firing is carried out in special rotary tube furnaces with direct heating, for example, using burners for liquid fuel. A mixture of sand, binders and pigments is fed into the furnace through a buffer hopper using a screw conveyor. Experts advise to dry the mixture before entering the furnace with hot exhaust gases. Thus, it is possible to significantly improve the characteristics of the raw material - its flowability and facilitate the process of passing the mixture through pipes (this is especially true if small rotary tube furnaces about five meters long are used for firing). In most cases, kilns from five to ten meters in length and diameters from 0.8 to 1.2 meters are used for firing. Larger kilns are significantly more expensive, but their advantages are a more even sand firing and easier handling. The firing time is about five minutes, with 2-3 minutes of this time the sand is exposed to maximum temperature.
The third stage is cooling and storage. When colored sand is discharged from the furnace, its temperature is around 900 ° C. Therefore, before sending it to the warehouse, the sand is additionally cooled. When cooling naturally, this process takes too much time, since sand has a high ability to retain heat for a relatively long time. Sand can be cooled directly at the outlet of the furnace, where a drum cooled by water is installed, or on vibrating troughs, on which sand is distributed in a thinner layer. Sand can be stored in two ways in warehouses. The most common and inexpensive option is to store sand in open crates. A more expensive way of organizing storage is in special bins in which sand is transported using elevators and in which it is sorted by color tones. From the hopper, sand is conveyed as necessary by the conveyor to the place of packaging. Part of the equipment necessary for the production of colored sand is purchased abroad (mainly in China), part - in our country, part is made by production companies independently or on order. Companies that sell colored sand use, among other things, standard lines for the production of building sand and gravel with different sizes, which usually consist of a feeder, a jaw crusher, equipment for the production of sand or a rotary crusher, a vibrating screen and a sand washer . If you plan to purchase ready-made and recycled sand, then most of this equipment you will not need. Pigments for coloring sand are purchased mainly from domestic manufacturers. When developing a color palette of products, manufacturers mix pigments of different colors in order to achieve a more stable and bright color. For this, special tables are used.
Finished colored quartz sand is sold in large quantities to construction companies and companies working in the glass industry. Quartz sand acts as the main component for the manufacture of various types of glasses (technical, sheet window, classic, specific laboratory, medical, perfume, etc.). Also, colored sand is used in large, medium and small castings (iron and steel). Recently, colored sand has received another scope. It is used for decorative works (including for the manufacture of paintings) and for creativity. It is bought by numerous sand animation studios and manufacturers of children's art kits, as well as floristic companies, landscape design and interior design studios, and artificial stone manufacturers.
Starting capital for organizing the production of colored sand is several million rubles. The exact amount depends on the volume of production and assortment. According to entrepreneurs, you can start a business with 350-500 thousand rubles, but in this case you should not count on quick payback and high profits. The range of companies that produce such products is not limited to sand alone and includes, in addition, dry building mixes, abrasive powders, various finishing materials, etc. In addition, they can provide some additional services: production of dry building mixes according to customer recipes, sandblasting, drying of bulk materials, etc.
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