Paronyms clay - clay. Dust Fighting dust while sculpting

Today we will talk about the pressing problem of every master involved in modeling from polymer clay, especially self-hardening. It is to cold porcelain that dust, villi, and wool especially stick.

I noticed that the softer and more plastic the mass for modeling, the more debris it attracts. And vice versa - a tight “casserole” or the same “modena” (yes! I finally tried it!), Which, in comparison with my samovar HF, is much harder, almost does not get dirty while working with them.

From personal experience

Previously, when there was only one table for intellectual work (which feeds) and creative work (which pleases), one had to be very nervous about dust. The fact is that there were two computers and an amplifier on the table - each of the devices has a cooler that drives dust very conscientiously.

Literally after a couple of minutes of working with floristic clay, the villi of all colors, sizes and origins began to attack the future flower. I could not blind the snowdrops just because of this - the white HF instantly overgrown with mud.

At first I thought that my personal curvature was to blame. And then some wonderful people gave me a separate table! (and not only, but now we are talking about the table!). As a gift, I blinded as a response gesture, albeit a small one.

So, when I began to sculpt away from technology, I was surprised - there was very little dust. And thanks to a number of tricks, it was possible to reduce the number of villi to a minimum. And now let's get to the point!

Dust control while sculpting

So that the villi and other muck do not stick to cold porcelain and do not spoil the pleasure of doing ceramic floristry, the following will help:

it is desirable to create at a table specially designated for this, away from fans, coolers (they are in all equipment and laptops too);
before starting sculpting, it is important to always wipe the table and adjacent surfaces with wet wipes;
it is useful to wipe and tools;
the file in which we roll out the clay needs to be changed as often as possible - it electrifies the dust on itself at breakneck speed;
wet wipes should be at hand at all times to wipe fingers on them before contact with HF;
it is advisable to roll the sleeves and the upper part of the clothing with a sticky roller in general, this is especially true if there is a fluffy pet in the house.
it is convenient to remove the villi from rolled clay with a needle;
it is best to roll out the modeling mass in a file or office folder so that contact with the rolling pin is indirect;
hands should be washed as often as possible;
using an anti-static spray usually does not help with dust control during flower sculpting.

Let me also remind you that in the process of cooking cold porcelain, or rather, kneading the mass, the surface must be perfectly clean. To do this, I cover it with a disposable film or a new cut file, fixing it with tape around the edges. I put plastic gloves on my hands - also new and disposable. Thanks to this, no dust and villi remain on the finished cold porcelain.

About the so-called. I already wrote about the “hygienic part” in an article about for beginners to engage in ceramic floristry: there is a food film, and files, and napkins, and cream in question. And also about

Clay and dust-like particles on the surface of sand grains prevent strong adhesion of grains to cement stone, reducing the strength of concrete.

To determine the content of clay and dust, 0.5 kg of dry sand is placed in a metal bowl, which is filled with water so that the height of the water layer above the sand is at least 5 cm. Then the sand in the bowl is shaken with a wooden spatula and left alone for 2 minutes. for sedimentation of sand particles, after which the muddy water is drained, the bowl is filled with water again, mixing, settling and draining the water are carried out.

The last operation must be carried out carefully to avoid the entrainment of grains of sand. The sand is washed until the water above the sand after mixing is clear. The washed sand is dried to constant weight. The content of clay and dust G is determined with an accuracy of 0.1%:

G \u003d (M-M 1) * 100 / M,

where M And M 1- mass of sand, respectively, before and after elutriation and drying, kg.

The experiments carried out allow us to conclude that the sand meets the requirements of GOST and its suitability for practical use.

In addition to these parameters, qualitative samples can be used to establish the content of organic impurities and the presence of sulfate salts in the sand, soluble in water.

Study of the grain composition and basic properties of coarse aggregate (crushed stone, gravel)

Objective- study of the properties of coarse aggregate (grain composition, bulk and bulk mass, intergranular voidness, the content of lamellar and acicular grains, dusty and clay particles), methods of its testing and GOST requirements for this material.

General information

gravel called loose material formed as a result of natural destruction (weathering) of rocks. It consists of more or less rounded grains with a size of 5-70 mm (GOST 8268-93. Gravel for construction work. Specifications).

Depending on the origin, there are ravine (mountain), river and sea gravel. Grains of river and sea gravel have a more rounded shape, which somewhat reduces the adhesion strength with cement mortar, and, consequently, the strength of concrete.

For massive structures (dams) and with a rare arrangement of reinforcement of reinforced concrete structures, gravel with a grain size of up to 120-150 mm can be used.

For the preparation of concrete, it is desirable to use gravel of optimal grain composition. Voidness in gravel should not exceed 45%. Flaky or lamellar and acicular forms of gravel are worse than cuboid or tetrahedral.

The strength of gravel should be 20-50% greater than the strength of the designed concrete grade.

In gravel, no more than 1% (by mass) of clay and dusty impurities is allowed, the amount of which is determined by elutriation.

rubble loose material obtained as a result of crushing rocks with a compressive strength of 20 to 120 MPa is called (GOST 8267-93. Crushed stone from natural stone for construction work. Specifications). Pieces of crushed stone have an acute-angled shape and sizes from 5 to 70 mm.

Pieces close in shape to a cube or tetrahedron are better for use than pieces of a flat and needle shape, because. they break easily.

Crushed stone is prepared from igneous rocks: granite, diabase, syenite etc., as well as from dense sedimentary rocks: sandstones, limestones, dolomites.

Limiting content of clay and dusty impurities:

For concrete grade 300 and above - 1% and 2%, respectively, for igneous and sedimentary rocks (by weight);

For concrete of lower grades, respectively, 2% and 3%.

R sh > 2 R b for concrete grade 300 and above;

R sh > 1.5 R b for concrete of lower grades;

where Rsh is the strength of the original rock for uniaxial compression.

Some Benefits gravel before rubble:

1) occurs in nature in a crushed state and it is necessary to crush only large pieces;

2) concrete mixtures have a slightly greater mobility than those prepared on crushed stone, due to better grain roundness;

3) has a smaller volume of voids due to rounded grains, resulting in a greater yield of concrete.

disadvantages gravel:

1) less adhesion to cement mortar, which reduces the strength of concrete;

2) high contamination with clay and other impurities requires gravel washing.

The choice of coarse aggregate is determined by economic feasibility. For high-strength concrete, it is better to use crushed stone.

Laboratory work provides for the definition:

1) grain composition of crushed stone;

2) bulk density (bulk density) of crushed stone grains;

3) average density of crushed stone grains;

4) intergranular voidness of crushed stone;

Based on the test results obtained, a conclusion is given on the compliance of crushed stone with the requirements of GOST.

Necessary devices and tools: a standard set of sieves, technical scales with weights, measuring vessels (1 l and 5 l), a sample of the test material, a drying cabinet.

In one of the sentences below, the underlined word is WRONGLY used. Correct the lexical error by choosing a paronym for the highlighted word. Write down the chosen word.

The impression of a new acquaintance I have left is very DOUBLE.

The editor demanded from the correspondent to rework the article so that the material was as INFORMATIONAL as possible, but at the same time small in volume.

Laureate and diploma winner of many theater festivals, the folk theater-studio decided to update the repertoire and in the near future will invite the audience to the premiere of the play.

Before me stood Dourov, a calm, well-groomed Dourov, a man who, apparently, was not too worried about my INTOLERANT attitude towards him.

Where the tanks made sharp turns, frozen CLAY dust rose into the air along with the snow.

Explanation (see also Rule below).

In the second sentence, instead of the word INFORMATION, it is appropriate to use the word INFORMATION.

Informational - informing about the state of affairs.

Informative - saturated with information, containing the greatest amount of information.

Answer: informative|informative.

Answer: informative | informative

Rule: Task 5. Use of paronyms

Paronyms are words that are similar in sound, but differ (partially or completely) in meaning.

Sometimes in our speech there are words that are similar in sound, but differ in shades of meaning or completely different in semantics. Among the lexical errors caused by ignorance of the exact meaning of the word, the most common errors are those associated with non-distinction, or confusion of paronyms.

Greek in origin, the linguistic term "paronym" literally means "the same name": Greek. para- the same onyma- name.

Paronyms can be called both single-root and similar-sounding words, which, for all their similarity, still differ in shades of meaning or denote different realities of reality.

"Analysis of the performance of task 5 showed that the difficulty for 40% of the examinees is not only the recognition of an error made when using paronyms, but also the selection of a paronym appropriate to the context for editing an example with an error, which reveals the narrowness of the vocabulary of the examinees." To help students in the selection of words-paronyms, the Dictionary of Paronyms is published annually. It is not for nothing that it is called the “dictionary”, since the “Dictionaries” contain thousands of paronymic words. The minimum included in the dictionary will be used in CIMs, but learning paronyms for task 5 is not an end in itself. This knowledge will help to avoid numerous speech errors in written works.

Please note that the RESHUEGE tasks contain tasks from previous years, and they contain words not from this list.

Write the word in the form required in the sentence. This requirement is based on the fact that the rules for filling out the forms indicate: if the short answer should be a word omitted in some sentence, then this word must be written in the form (gender, number, case, etc.) in which it should stand in a sentence. Dictionary of paronyms USE. Russian language. 2019 year. FIPI.

Subscription - subscriber

Artistic - Artistic

Poor - distressed

Irresponsible - irresponsible

swampy - swampy

grateful - grateful

charitable - benevolent

former - former

Inhale - sigh

Age-old - eternal

Great - majestic

fill up - fill up - fill up - fill up - fill up - fill up

hostile - hostile

choosing - choosing

Benefit - Profitability

Issuance - return - transfer - distribution

payout - pay - pay - pay

pay - pay - pay - pay - pay

grow - grow - grow

Growing - building - growing

High - high-rise

Warranty - guaranteed

Harmonic - harmonious

Clay - clay

annual - annual - annual

pride - pride

Humanism - humanity

humanistic - humanitarian - humane

Binary - double - dual - double - double - doubled

Valid - Valid - Valid

businesslike - businesslike - businesslike - businesslike

Democratic - Democratic

Dictation - dictation

diplomat - diplomat

Diplomatic - diplomatic

Long - long

kind - kind

trusting - trusting

rainy - rainy

dramatic - dramatic

friendly - friendly - friendly

Single - the only one

desired - desirable

cruel - tough

vital - worldly

Housing - residential

to fence off - to fence off - to fence off - to fence off - to fence off

lower - lower - lower

pay - pay

Fill - fill - fill

Filled - filled - full

initiator - instigator

bestial - brutal

sound - sonorous

Visual - spectator

inventive - inventive

Informative - informational - information - awareness

ironic - ironic

Artful - artificial

Executive - performing

Outgoing - Outgoing

Stony - stone

Comfortable - comfortable

equestrian - equine

Chunky - Root - Root

bone - bone

colorful - coloring - dyed

Lacquered - lacquered

Ice - ice

wooded - wooded

personal - personal

microscopic - microscopic

Ice cream - freezer - frosty

put on - put on

Availability - cash

Reminder - mention

Ignorant - ignorant

intolerable - impatient - intolerant

Unsuccessful - unfortunate

accused - accused

snippet - snippet

embrace - embrace

limit - limit - limit

Call - response

Organic - organic

Selective - qualifying

Deflection - evasion

evade - evade

Distinguish (s) - distinguish (s)

Difference - difference

memorable - memorable

endure - endure

Buying - buying - buying

Populist - popular

venerable - respectful - honorary

practical - practical

Submit - Submit

representative - representative

Recognized - grateful

Productive - grocery

Productive - production - performance

enlightened - enlightened

journalistic - journalistic

timid - scared

Irritability - irritability

rhythmic - rhythmic

romantic - romantic

secretive - hidden

vocabulary - verbal

resistance - resistance

Neighbor - neighbor

Comparable - Comparative

stage - stage

Technical - technical

Lucky - Lucky

Humiliated - humiliating

actual - actual

predatory - predatory

royal - regal - reigning

whole - whole - whole

Economic - economical - economical

Aesthetic - aesthetic

Ethical - ethical

Effective - effective

Efficiency - showiness

Clay- this is a fine-grained sedimentary rock, dusty in a dry state, plastic when moistened.

Origin of clay.

Clay is a secondary product formed as a result of the destruction of rocks in the process of weathering. The main source of clayey formations are feldspars, the destruction of which under the influence of atmospheric agents forms silicates of the group of clay minerals. Some clays are formed during the local accumulation of these minerals, but most of them are sediments of water streams that accumulate on the bottom of lakes and seas.

In general, by origin and composition, all clays are divided into:

- sedimentary clays, formed as a result of the transfer to another place and the deposition there of clay and other products of the weathering crust. By origin, sedimentary clays are divided into marine clays deposited on the seabed and continental clays formed on the mainland.

Among marine clays, there are:

coastal- are formed in coastal zones (zones of resuspension) of the seas, open bays, river deltas. Often characterized by unsorted material. Quickly transition to sandy and coarse-grained varieties. Replaced along strike by sandy and carbonate deposits. Such clays are usually interbedded with sandstones, siltstones, coal seams, and carbonate rocks.
Lagoon- are formed in sea lagoons, semi-enclosed with a high concentration of salts or desalinated. In the first case, clays are heterogeneous in granulometric composition, are not sufficiently sorted, and wind up together with gypsum or salts. The clays of desalinated lagoons are usually fine-dispersed, thin-layered, contain inclusions of calcite, siderite, iron sulfides, etc. Among these clays there are refractory varieties.
Offshore- are formed at a depth of up to 200 m in the absence of currents. They are characterized by a homogeneous granulometric composition, large thickness (up to 100 m and more). Distributed over a large area.

Among the continental clays are:

Deluvial- are characterized by a mixed granulometric composition, its sharp variability and irregular bedding (sometimes absent).
Lake with a uniform granulometric composition and finely dispersed. All clay minerals are present in such clays, but kaolinite and hydromicas, as well as minerals of hydrous Fe and Al oxides, predominate in the clays of freshwater lakes, while minerals of the montmorillonite group and carbonates predominate in the clays of salt lakes. The best varieties of refractory clays belong to lake clays.
Proluvial formed by time streams. Very poor sorting.
River- developed in river terraces, especially in the floodplain. Usually poorly sorted. They quickly turn into sands and pebbles, most often unstratified.

Residual - clays resulting from the weathering of various rocks on land, and in the sea as a result of changes in lavas, their ashes and tuffs. Down the section, the residual clays gradually pass into the parent rocks. The granulometric composition of residual clays is variable - from finely dispersed varieties in the upper part of the deposit to uneven-grained ones in the lower part. Residual clays formed from acidic massive rocks are not plastic or have little plasticity; more plastic are clays that have arisen during the destruction of sedimentary clayey rocks. Continental residual clays include kaolins and other eluvial clays. In the Russian Federation, in addition to modern, ancient residual clays are widespread - in the Urals, in the West. and Vost. Siberia, (there are also many of them in Ukraine) - of great practical importance. In the areas mentioned above, mainly montmorillonite, nontronite, etc. clays appear on the basic rocks, and on medium and acidic ones - kaolins and hydromica clays. Marine residual clays form a group of bleaching clays composed of minerals of the montmorillonite group.

Clay is everywhere. Not in the sense - in every apartment and a plate of borscht, but in any country. And if there is not enough diamonds, yellow metal or black gold in some places, then there is enough clay everywhere. Which, in general, is not surprising - clay, sedimentary rock, is a stone worn by time and external influence to the state of powder. The last stage of stone evolution. Stone-sand-clay. However, the last one? And sand can be deposited into stone - golden and soft sandstone, and clay can become brick. Or a person. Who's lucky.

Clay is colored by the stone-creator and salts of iron, aluminum and similar minerals that are nearby. Various organisms multiply, live and die in clay. This is how red, yellow, blue, green, pink and other colored clays are obtained.

Previously, clay was mined along the banks of rivers and lakes. Or dug a hole specifically for it. Then it turned out to be possible not to dig clay on your own, but to buy it from a potter, for example. During our childhood, ordinary, red clay was dug out by ourselves, and noble white clay was bought in shops for artists or, especially pure, in a pharmacy. Now in the nigga little shop selling cosmetics, there is certainly clay. True, not quite in its pure form, but mixed with various detergents, moisturizers and nutrients.

Our land is rich in clay. Roads and paths pierced in loamy soil in the heat become sources of dust, and in slush - solid mud. Clay dust covered the traveler from head to toe and added domestic work to the housewives, whose house stood by the road. Surprisingly, near the roads, dressed in asphalt, the dust did not decrease. True, from red, he became black. Ledum, densely mixed with clay, not only interferes with walking a pedestrian and driving a wheel, but also does not mind swallowing a boot or a jeep if you are in the mood.

Clay consists of one or more minerals of the kaolinite group (derived from the name of the locality Kaolin in the People's Republic of China (PRC)), montmorillonite, or other layered aluminosilicates (clay minerals), but may contain both sand and carbonate particles. As a rule, the rock-forming mineral in clay is kaolinite, its composition is 47% silicon (IV) oxide (SiO 2), 39% aluminum oxide (Al 2 O 3) and 14% water (H 2 0). Al2O3 And SiO2- make up a significant part of the chemical composition of clay-forming minerals.

Clay particle diameter less than 0.005 mm; rocks consisting of larger particles are commonly classified as loess. Most of the clays are gray, but there are clays of white, red, yellow, brown, blue, green, purple and even black. The color is due to impurities of ions - chromophores, mainly iron in valence 3 (red, yellow) or 2 (green, bluish).

Dry clay absorbs water well, but when wet it becomes waterproof. After kneading and mixing, it acquires the ability to take on various forms and retain them after drying. This property is called plasticity. In addition, clay has a binding ability: with powdery solids (sand) it gives a homogeneous "dough", which also has plasticity, but to a lesser extent. Obviously, the more sand or water impurities in the clay, the lower the plasticity of the mixture.

By the nature of the clay are divided into "fat" and "skinny".

Clays with high plasticity are called "fatty" because when soaked they give a tactile sensation of a fatty substance. "Fatty" clay is shiny and slippery to the touch (if you take such clay on your teeth, it slides), contains few impurities. The dough "made from it is tender. A brick made of such clay cracks during drying and firing, and in order to avoid this, the so-called" lean "substances are added to the batch: sand," skinny "clay, burnt brick, pottery battle, sawdust and other

Clays with low plasticity or non-plasticity are called "skinny". They are rough to the touch, with a matte surface, and when rubbed with a finger, they easily crumble, separating earthy dust particles. "Skinny" clays contain a lot of impurities (they crunch on the teeth), when cut with a knife they do not give shavings. Brick made of "skinny" clay is fragile and crumbly.

An important property of clay is its relation to firing and, in general, to elevated temperature: if clay soaked in air hardens, dries and is easily rubbed into powder without undergoing any internal changes, then at high temperature chemical processes occur and the composition of the substance changes.

Clay melts at very high temperatures. The melting temperature (the beginning of melting) characterizes the fire resistance of clay, which is not the same for its various varieties. Rare varieties of clay require colossal heat for firing - up to 2000 ° C, which is difficult to obtain even in factory conditions. In this case, it becomes necessary to reduce the fire resistance. It is possible to reduce the reflow temperature by introducing additives of the following substances (up to 1% by weight): magnesia, iron oxide, lime. Such additives are called fluxes (fluxes).

The color of clays is varied: light gray, bluish, yellow, white, reddish, brown with various shades.

Minerals contained in clays:

Kaolinite (Al2O3 2SiO2 2H2O)
Andalusite, disthene and sillimanite (Al2O3 SiO2)
Halloysite (Al2O3 SiO2 H2O)
Hydrargillite (Al2O3 3H2O)
Diaspore (Al2O3 H2O)
Corundum (Al2O3)
Monothermite (0.20 Al2O3 2SiO2 1.5H2O)
Montmorillonite (MgO Al2O3 3SiO2 1.5H2O)
Muscovite (K2O Al2O3 6SiO2 2H2O)
Narkit (Al2O3 SiO2 2H2O)
Pyrophyllite (Al2O3 4SiO2 H2O)

Minerals contaminating clays and kaolins:

Quartz(SiO2)
gypsum (CaSO4 2H2O)
dolomite (MgO CaO CO2)
Calcite (CaO CO2)
Glauconite (K2O Fe2O3 4SiO2 10H2O)
Limonite (Fe2O3 3H2O)
Magnetite (FeO Fe2O3)
Marcasite (FeS2)
Pyrite (FeS2)
Rutile (TiO2)
Serpentine (3MgO 2SiO2 2H2O)
Siderite (FeO CO2)

Clay appeared on earth many thousands of years ago. Its "parents" are rock-forming minerals known in geology - kaolinites, spars, some varieties of mica, limestones and marbles. Under certain conditions, even some types of sand are transformed into clay. All known rocks that have geological outcrops on the surface of the earth are subject to the influence of the elements - rain, whirlwind, snow and flood waters.

Temperature fluctuations day and night, heating of the rock by sunlight contribute to the appearance of microcracks. Water gets into the formed cracks and, freezing, breaks the surface of the stone, forming a large amount of the smallest dust on it. Natural cyclones crush and grind the dust into even finer dust. Where the cyclone changes direction or simply subsides, huge accumulations of rock particles form over time. They are compressed, soaked in water, and the result is clay.

Depending on what rock clay is formed from and how it is formed, it acquires different colors. The most common are yellow, red, white, blue, green, dark brown and black clays. All colors, except black, brown and red, speak of the deep origin of clay.

The colors of clay are determined by the presence of the following salts in it:

red clay - potassium, iron;
greenish clay - copper, ferrous iron;
blue clay - cobalt, cadmium;
dark brown and black clay - carbon, iron;
yellow clay - sodium, ferric iron, sulfur and its salts.

Various colored clays.

We can also give an industrial classification of clays, which is based on the assessment of these clays according to a combination of a number of features. For example, this is the appearance of the product, color, sintering (melting) interval, resistance of the product to a sharp change in temperature, as well as the strength of the product to impact. According to these features, you can determine the name of the clay and its purpose:

china clay
faience clay
white-burning clay
brick and tile clay
pipe clay
clinker clay
capsule clay
terracotta clay

Practical use of clay.

Clays are widely used in industry (in the production of ceramic tiles, refractories, fine ceramics, porcelain and faience and sanitary wares), construction (production of bricks, expanded clay and other building materials), for domestic needs, in cosmetics and as a material for artwork ( modeling). Expanded clay gravel and sand produced from expanded clay by annealing with swelling are widely used in the production of building materials (expanded concrete, expanded clay concrete blocks, wall panels, etc.) and as a heat and sound insulating material. This is a light porous building material obtained by firing fusible clay. Has the form of oval granules. It is also produced in the form of sand - expanded clay sand.

Depending on the clay processing mode, expanded clay of various bulk density (bulk density) is obtained - from 200 to 400 kg / M3 and more. Expanded clay has high heat and noise insulating properties and is used mainly as a porous filler for lightweight concrete, which has no serious alternative. Walls made of expanded clay concrete are durable, have high sanitary and hygienic characteristics, and structures made of expanded clay concrete, built more than 50 years ago, are still in operation today. Housing built from prefabricated expanded clay concrete is cheap, high quality and affordable. The largest manufacturer of expanded clay is Russia.

Clay is the basis of pottery and brick production. When mixed with water, clay forms a doughy plastic mass suitable for further processing. Depending on the place of origin, natural raw materials have significant differences. One can be used in its pure form, the other must be sieved and mixed to obtain a material suitable for the manufacture of various trade items.

Natural red clay.

In nature, this clay has a greenish-brown color, which gives it iron oxide (Fe2O3), which makes up 5-8% of the total mass. During firing, depending on the temperature or type of kiln, the clay acquires a red or whitish color. It is easily kneaded and withstands heating of no more than 1050-1100 C. The high elasticity of this type of raw material allows it to be used for working with clay plates or for modeling small sculptures.

White clay.

Its deposits are found all over the world. When wet, it is light gray, and after firing it becomes whitish or ivory. White clay is characterized by elasticity and translucency due to the absence of iron oxide in its composition.

Clay is used to make dishes, tiles and sanitary ware or for crafts from clay plates. Firing temperature: 1050-1150 °C. Before glazing, it is recommended to work in an oven at a temperature of 900-1000 °C. (The firing of unglazed porcelain is called biscuit firing.)

Porous ceramic mass.

Clay for ceramics is a white mass with a moderate calcium content and increased porosity. Its natural color is pure white to greenish brown. Fired at low temperatures. Unfired clay is recommended, as for some glazes a single firing is not enough.

Majolica is a type of raw material made from fusible clay rocks with a high content of white alumina, fired at a low temperature and covered with a glaze containing tin.

The name "majolica" comes from the island of Mallorca, where it was first used by the sculptor Florentino Luca de la Robbia (1400-1481). Later, this technique was widely used in Italy. Ceramic trade items made of majolica were also called earthenware, since their production began in the workshops for the production of earthenware utensils.

Stone ceramic mass.

The basis of this raw material is fireclay, quartz, kaolin and feldspar. When wet, it has a black-brown color, and when raw fired, it is ivory. When glaze is applied, stoneware turns into a durable, waterproof and fireproof product. It can be very thin, opaque or in the form of a homogeneous, tightly sintered mass. Recommended firing temperature: 1100-1300 °C. If it is broken, the clay may crumble. The material is used in various technologies for the manufacture of pottery trade items from lamellar clay and for modeling. A distinction is made between red clay trade items and stoneware, depending on their technical properties.

Clay for porcelain trade items consists of kaolin, quartz and feldspar. It does not contain iron oxide. When wet it has a light gray color, after firing it is white. Recommended firing temperature: 1300-1400 °C. This type of raw material has elasticity. Working with it on the potter's wheel requires high technical costs, so it is better to use ready-made forms. This is a hard, non-porous clay (with low water absorption. - Ed.). After firing, porcelain becomes transparent. Glaze firing takes place at a temperature of 900-1000 °C.

Various trade items made of porcelain molded and fired at 1400°C.

Coarse-pored coarse-grained ceramic materials are used for the manufacture of large-sized trade items in construction, small-form architecture, etc. These grades withstand high temperatures and thermal fluctuations. Their plasticity depends on the content of quartz and aluminum (silica and alumina. - Ed.) in the rock. In the general structure there is a lot of alumina with a high content of chamotte. The melting point ranges from 1440 to 1600 °C. The material sinters well and shrinks slightly, so it is used to create large objects and large-format wall panels. When making art objects, the temperature should not exceed 1300°C.

This is a clay mass containing oxide or colorful pigment, which is a homogeneous mixture. If, penetrating deep into the clay, part of the paint remains in suspension, then the even tone of the raw material may be disturbed. Both colored and ordinary white or porous clay can be purchased at specialized stores.

Masses with colored pigment.

Pigments are inorganic compounds that color clay and glaze. Pigments can be divided into two groups: oxides and colorants. Oxides are the main material of natural origin, which is formed among the rocks of the earth's crust, cleaned and sprayed. The most commonly used are: copper oxide, which takes on a green color in an oxidizing firing environment; cobalt oxide, forming blue tones; iron oxide, which, when mixed with glaze, gives blue tones, and when mixed with clay, engobes of earthy tones. Chromium oxide gives clay an olive green color, magnesium oxide browns and purples, and nickel oxide grayish greens. All these oxides can be mixed with clay in a proportion of 0.5-6%. If their percentage is exceeded, the oxide will act as a flux, lowering the melting point of the clay. When painting items of trade, the temperature should not exceed 1020 ° C, otherwise firing will not work. The second group is dyes. They are obtained industrially or by mechanical processing of natural materials, which represent a full range of colors. Dyes are mixed with clay in a proportion of 5-20%, which determines the light or dark tone of the material. All specialist shops carry pigments and dyes for both clay and engobe.

The preparation of ceramic mass requires a lot of attention. It can be composed in two ways, which give completely different results. A more logical and reliable way: apply dyes under pressure. A simpler and, of course, less reliable method is to mix the dyes into the clay by hand. The second method is used if there is no exact idea of the final coloring results, or if there is a need to repeat some specific colors.

Technical ceramics.

Technical ceramics - a large group of ceramic trade items and materials obtained by heat treatment of a mass of a given chemical composition from mineral raw materials and other high quality raw materials that have the necessary strength, electrical properties (high volume and surface resistivity, high electrical strength, small tangent of the angle dielectric losses).

Cement production.

To make cement, calcium carbonate and clay are first extracted from quarries. Calcium carbonate (approximately 75% of the amount) is crushed and thoroughly mixed with clay (approximately 25% of the mixture). Dosing of raw materials is an extremely difficult process, since the lime content must correspond to a given amount with an accuracy of 0.1%.

These ratios are defined in the literature by the concepts of "calcareous", "siliceous" and "aluminous" modules. Since the chemical composition of the raw materials constantly fluctuates due to geological origin, it is easy to understand how difficult it is to maintain a constant modulus. In modern cement plants, computer-assisted control in combination with automatic analysis methods has proven itself.

Correctly composed sludge, prepared depending on the chosen technology (dry or wet method), is introduced into a rotary kiln (up to 200 m long and up to 2-7 m in diameter) and fired at a temperature of about 1450 °C - the so-called sintering temperature. At this temperature, the material begins to melt (sinter), it leaves the furnace in the form of more or less large lumps of clinker (sometimes called Portland cement clinker). Roasting takes place.

As a result of these reactions, clinker materials are formed. After leaving the rotary kiln, the clinker enters the cooler, where it is rapidly cooled from 1300 to 130 °C. After cooling, the clinker is crushed with a small addition of gypsum (maximum 6%). The grain size of cement lies in the range from 1 to 100 microns. It is better illustrated by the concept of "specific surface area". If we sum up the surface area of the grains in one gram of cement, then, depending on the thickness of the grinding of the cement, values from 2000 to 5000 cm² (0.2-0.5 m²) will be obtained. The predominant part of the cement in special containers is transported by road or rail. All overloads are performed pneumatically. A minority of cement products are delivered in moisture- and tear-resistant paper bags. Cement is stored at construction sites mainly in liquid and dry states.

Auxiliary information.

Dust of different origin:

Grain:

MPC.z.=4 mg/m³

MPCm.r.=0.5 mg/m³

MACc.s.=0.15 mg/m³

Flour, woody, etc.:

MPC.z.=6 mg/m³

MPCm.r.=1 mg/m³

MACc.s.=0.4 mg/m³

Cotton, linen, wool, down:

MPC.z.=2 mg/m³

MPCm.r.=0.2 mg/m³

MACc.s.=0.05 mg/m³

Hazard class - 3 (Moderately hazardous substances)

Cement, limestone, chalk, sand, clay, ash:

MPC.z.=4 mg/m³

MPCm.r.=0.3 mg/m³

MACc.s.=0.1 mg/m³

Hazard class - 3 (Moderately hazardous substances)

Emission dust from tobacco factories with nicotine content up to 2.7%

MPCm.r. =0.0008 mg/m³

MPCs.s. =0.0004 mg/m³

Hazard class - 4 (Low hazardous substances)

Polymetallic dust with lead content up to 1% (asbestos belongs to the same hazard class)

MPC.z.=0.005 mg/m³

MPCm.r.=not allowed

MACc.s.=0.0001 mg/m³

Hazard class - 1 (Extremely hazardous substances)

Separately, I want to say a few words about dust. Yes, yes, about the most common ubiquitous dust. Did you know that it is a group 1 carcinogen and there are well-defined maximum permissible concentrations for it?

Why is dust important? Why is so much attention paid to dust control in the world?

Dust is small solid particles of organic or mineral origin. Dust includes particles of average diameter from fractions of a micron to a maximum of 0.1 mm. Airborne particulate matter less than 0.1 microns is called smoke. Particles larger than 0.1 mm transform the material into a sand discharge, which has dimensions from 0.1 to 5 mm. Dust particles smaller than 10 microns constantly float in the air, particles from 10 to 50 microns settle gradually, and larger particles settle almost immediately. Under the action of moisture, dust usually turns into dirt.

By origin, dust is divided into terrestrial and cosmic, natural and artificial, mineral and organic, plant and animal, industrial, municipal, etc. Up to 75% of the total amount of dust in the atmosphere consists of inorganic substances. The main sources of dust are the processes of weathering of rocks and soil cover, various plants, living and dead organisms and their remains; dust is formed in conflagrations, etc. A number of organic dust ingredients, such as plant and flower pollen, spores, fungi, molds, microorganisms, etc., can serve as allergens and, if inhaled, cause allergic diseases in individuals.

In cities, the main sources of atmospheric air pollution are: dust from industrial enterprises and boiler houses, emitting ash, soot, products of incomplete combustion of fuel in the form of soot and adsorbed resinous substances containing 3,4-benzpyrene through chimneys; street dust that rises into the air when people and especially vehicles move. Dusty air worsens climatic conditions, reduces solar illumination.

Dust has many influences, but almost all of them are negative. The most dangerous are dust particles of 10 microns (PM10) or less. As with inhalation in a clinic or at home, the drug is sprayed into droplets of just such a size (on the order of 2-10 microns, depending on the type of inhaler), which ensures that these drugs penetrate very deeply into the body, and sometimes directly into the blood. There is no difference when inhaling air saturated with dust, but instead of medicines, anything gets into the body, heavy metals, soot with unburned petroleum products, microbes ...

Dust particles adsorb on their surface various gases, vapors, radioactive substances, microorganisms, ions and free radicals (the latter have a very high chemical activity and enhance the harmful effects of dust on the body). Dust becomes especially dangerous when toxic and radioactive substances, pathogenic microorganisms and viruses are adsorbed on its particles.

In our society, the impact of dust on health is given little attention, however, as well as ecology in general. However, many studies have been conducted in Europe and the USA. One of the last was held between 2002 and 2004 in 13 Italian cities. PM10 dust values ranged from 26.3 µg/m³ to 61.1 µg/m³. The number of deaths caused by dust concentrations above 20 µg/m³ was 8220 per year, or 9% of the total number of deaths (excluding accidents), for residents over 30 years of age. This is mainly death from lung cancer (742 cases per year), heart attack (2562), stroke (329). As well as cardiovascular and respiratory diseases.
A detailed report in English is available.
In this case, it is important to say that in Russia there was a document "Supplement No. 8 to GN 2.1.6.1338-03 "Maximum Permissible Concentrations (MPC) of pollutants in the atmospheric air of populated areas"" according to which the permissible average daily dust concentration of the PM10 fraction is 60 μg / m³. According to the EU Directive 2008/50/EC in Europe, the average daily MPC PM10 is 50 µg/m³, with an allowance that for about 35 days a year it can be up to 75 µg/m³. In Germany, everything is stricter: for PM10 - the limit is 40 μg / m³, with a tolerance of 35 days a year - 50 - μg / m³.
And in Lithuania, in addition to the data, there are such recommendations: at PM10 concentrations in the range from 51 to 100, active outdoor recreation is not recommended, and use of one's own vehicles (so as not to further increase the concentration of dust). Even in the range of 31 to 51, children and the elderly are encouraged to avoid long walks along busy roads.

From 40 to 80% of dust is retained in the respiratory organs, depending on the degree of dispersion. The largest amount of dust penetrating into the pulmonary alveoli has sizes from 0.1 to 10 microns. The exhaled air contains 5-10% of dust particles, the rest of the dust is partially excreted by the ciliated epithelium, and most of it is swallowed and enters the gastrointestinal tract. Dust irritates the skin, organs of vision and hearing. Prolonged breathing in dusty air can lead to an increase in diseases (in particular, respiratory organs), especially in children and adolescents. In the lung alveoli, special cells (phagocytes) capture dust particles and dissolve them or transfer them to the bronchi or lymphatics, thus removing them from the lungs. A significant part of the trapped dust is released when sneezing and coughing.

In a tightly locked apartment with closed windows, about 12,000 dust particles settle in two weeks per 1 cm² of the floor and the horizontal surface of the furniture. House dust can contain pet hair and dander, feather fragments, particles of insects, human hair and skin, mold spores, nylon, fiberglass, sand, particles of fabrics and paper, the smallest fragments of materials from which walls, furniture and household items are made. This dust contains 35% mineral particles, 12% textile and paper fibers, 19% leather flakes, 7% pollen, 3% soot particles and smoke. The remaining 24% is of unknown origin and even space dust. Do you think I've gone too far about space dust? If you believe Wikipedia, 40,000 tons of space dust each year settles on planet Earth. Most of the dust enters a person's home with air, and not because of dirty shoes, clothes, etc.

By the way, dust is sometimes useful! In addition to spraying medicines in the inhaler, dust can contain beneficial sea salts and minerals. True, far from the sources of such dust, their content is negligible. The amount of dust in the atmosphere also has a big impact on the climate. Dust particles absorb some of the solar radiation, and also participate in the formation of clouds, being condensation nuclei.

For the scale of any phobias, I will give you the following text: During its life, a pillow absorbs several tons of liquid that evaporates from our skin. Ticks-saprophytes living in it - 0.3 mm arthropods, cause the most severe forms of allergies, feed on scales from our skin or microparticles of blood that are on feathers. An old feather pillow contains 10% mite excrement. In 1 gram of mattress dust live from 200 to 15 thousand mites-saprophytes, and in a double bed there are 500 million of them. Tick allergy is detected in 70% of children with bronchial asthma. With tick-borne bronchial asthma, exacerbations occur in the spring-autumn period, especially at night. To date, about 150 species of mites have been found in house dust. They are called dermatophagoid or pyroglyphid mites.

And don't be surprised if you're allergic!

Fire and explosion hazards of dust

Dust can burn, ignite spontaneously, form explosive mixtures with air, even in cases where the source material is non-combustible! The reason is an increase in the total surface and free energy surface of the system, which increases the chemical activity, in particular, the ability to oxidize with the release of heat.

Dust suspended in the air is explosive, and settled dust is a fire hazard! At the same time, when the settled dust rises as a result of combustion or a local microexplosion, impact, etc. it can pass into a suspended state and become a medium for a subsequent explosion or even a series of explosions.

Explosive and flammable dust is divided into 4 classes:

1 class - dust with a lower explosive limit less than 15 g/m³ . This includes dusty substances such as anthracene, rosin, slag, ebonite, sulfur, peat, linen fire, powdered milk, sugar, cotton.

Class 2 - explosive dusts with a lower explosive limit at a concentration of 16 to 65 g / m³. An example of a related inorganic dust is aluminum powder. Organic substances in this category include pulverized gas soot, shale flour, wood flour, mill dust, wheat waste, peas, sunflower cake, starch and tea dust.

Class 3 - the most flammable dust, which can ignite spontaneously at temperatures up to 250 ° C. This includes tobacco, zinc, coal dust.

Class 4 - dust with a self-ignition temperature above 250 ° C, for example, sawdust.

Of course, not all types of dust are listed. The finer the dust, the more porous its structure, the more chemically active and explosive it is. The possibility of an explosion is facilitated by the presence of an electric charge on dust particles, as well as the contact of dust with a heat source (ignition), the formation of sparks, and contact with a flame. Naturally, only dusty air, in which there is a sufficient percentage of oxygen, can explode and ignite.

The explosiveness of dust, as well as the strength of the explosion and the temperature of self-ignition, are significantly affected by the dispersion of particles. So, with a decrease in dispersion, the pressure at the site of the explosion increases, and the self-ignition temperature of the dust decreases. The explosion hazard of dust also depends on the presence of inert impurities, humidity and the release of combustible gases in it. For example, when the oxygen content in the air is less than 10%, dust ignition does not occur. However, the possibility of emitting volatile gases from dust dramatically increases the fire and explosion hazard!

Since dust explosions can occur in apparatus, fans, air ducts, etc., explosion-proof apparatus must be used.

Various methods are used to determine the amount of dust in the air: weight; conimetric, in which the number of dust particles in the air is determined; photometric, based on measuring the decrease in the intensity of light passing through dusty air, and others.

You can convert weight data into counting data. When translating, consider that 1 mg/m³ corresponds to approximately 200 dust particles (from 0.4 to 2 microns in diameter) per 1 cm³ . In the practice of dust cleaning, it is necessary to take into account the disperse composition, to divide the dust into fractions according to the particle size. Fractional composition of dust is expressed in microns and subdivided into fractions with sizes: 0-5; 5-10; 10-20; 20-40; 40-60 and more than 60 microns.

To assess the dust content of atmospheric air, it is often expressed by the amount of dust deposited on a unit surface in a certain time. To determine the amount of dust falling over a certain time from atmospheric air (aerosol) polluted with dust, a can-sedimentary sampling method is used. Dust particles arbitrarily settling from the air are collected in cylindrical cans (made of plastic or faience) 25-30 cm high and 20-30 cm in diameter. The cans are installed on special poles 3 m high or on the roofs of houses. To protect the can from the action of the wind, it is placed in a plywood box with an edge of 0.6 m, open on top. The cans are put up for a period of 15 to 90 days. At the end of the term, the dust settled in the jar is weighed and thus the amount of dust settled per unit of time per unit area is obtained. This value is expressed in grams per 1 m² or in tons per 1 km² in year. This method can determine the amount of settling dust at different distances from the source of air pollution.