RU2003425C1 - Complex additive for production of sand-clay molding mixtures - Google Patents

Description

asphaltenes - the highest molecular and high boiling substances of oil with a content of 80-89 wt.% carbon and 7-9.0 wt.% hydrogen. At the same time, the absence of free mineral oil in the additive prevents a significant increase in the gas content of the molding compounds. (Posadov I.A. and Pokonova Yu.V. The structure of oil asphalts. L .: ITI, 1977). Petroleum asphaltite obtained by the Doben process at the Ufa experimental plant BashNII NL having the following fractional composition, wt.%: Can be used as a source of asphaltite production.

Asphaltene57.0

Resins27.0

Mineral oils 16.0

It is known to use asphaltenes proper obtained by deasphalting residual products of oil refining with pentane (German Patent No. 1955248, CL, B 22 C 1/00) to improve the knockability of liquid glass molding mixtures. Their use as a non-stick additive for sand-clay mixtures is unknown.

The use of the proposed additive in the amount of 0.05-5.0 wt.% As a composition of the moldable mixture as a flame retardant anti-burn-off agent is sufficient to produce castings without burn-out and squeezes.

The supposed addition ensures the achievement of the set goal with optimal physicomechanical and technological properties of the molding mixture, minimal gas content, good fillability of the mold (formability), and absence of surface defects such as burn-in and bumps on castings.

An increase in the amount of asphaltite in the composition of the complex additive above the upper limit is impractical due to a slight increase in the caking of the mixture during transportation (increase in caking index).

A decrease in the content of asphaltite in the composition of the complex additive reduces its non-stick and anti-burnout effects and worsens the technological properties.

With an increase in the content of ground coal above the upper limit, accordingly, the asphaltite content decreases, the non-stick and anti-burn effects of the complex additive decrease, and the technological properties of the mixture deteriorate

A decrease in the carbon content of the complex additive results in an effect similar to a corresponding increase in the content of asphaltite in it.

The procedure for preparing a complex additive is common in the technology for the preparation of coal powders and compositions, for example, fuel briquettes, and the introduction of molding compounds into the practice of preparing them using standard mixers and dispensers.

0 When using a comprehensive anti-stick-anti-suppressant additive as a component of the molding mixture, the mixture, sand,

5 clay or bentonite, a complex additive, if necessary other additives, for example, starchite and the required amount of water. The mixing time of the mixture is determined by the type of mixer and the factory instructions.

Table 3 shows the compositions of complex additives, where 2, 3, 4 are the compositions of additives with the proposed ratio of components; 5, 6 - compositions with exorbitant values of the input components: 1 - the composition of the additive according to the prototype.

Table 4 shows the test results of the properties of the additives and the mixtures made with their use with a compressibility of 450 47%.

In a laboratory screw mixer 60 rpm, ground coal and asphaltite were sequentially loaded in the required proportions and mixed for 30

5 minutes. The finished additive was then used to prepare the molding sand and carry out the required analyzes.

For the preparation of molding sand, laboratory runners mod. 017 were used

0 mixing capacity up to b kg. 061K02B quartz ramen sand, Dashukovsky activated bentonite, a non-stick additive were successively introduced into the runners, they were mixed for 2 minutes, and then

5, the required amount of water was introduced and the mixture was stirred for another 8 minutes. The non-stick effect of additives was determined by the yield of pyrolytic carbon according to the Kolorz method. The method is coking.

0 air-dry samples of carbon material placed in a special device consisting of a quartz crucible and a tube in a muffle furnace heated to a temperature of 875 ± 10 ° C. Highlighting

5, when the carbon substance is thermally degraded, the gases pass through quartz wool preheated to 875 ° C and placed in a tube, on the surface of which hydrocarbons decompose to form brilliant carbon. After 3 minutes in the oven, the tube is removed from the muffle, cooled and weighed. The ratio of the mass of the released brilliant carbon to the mass of the dry sample (in%) characterizes the yield of brilliant carbon from this material.

To determine the softening temperature, a weighed portion of an additive weighing 2 g in a porcelain crucible was placed in an oven and heated for 30 minutes at 100-250 ° C with an interval of about 10 ° C. After heating at the appropriate temperature, the sample was removed from the furnace and its phase state was determined using a special needle. The temperature at which the transition of the additive to the visco-plastic state was observed was taken as the softening temperature of the additive.

To determine the tendency of non-stick additives to caking, they were poured onto a steel sleeve with a diameter of 40 mm and sealed with one blow on a laboratory head with a load weight of 6.7 kg and a drop height of 50 mm. Then, the samples together with the sleeve were placed in a thermostat and kept there at 50 ° C for 1 h. After cooling, the samples were removed from the sleeve and placed for 30 s on a No. 2,5 sieve of a standard device for sieving bulk materials. The caking index was estimated by the ratio of the material remaining on the No. 2.5 sieve to the initial mass of the sample, expressed in%. The fractional analysis of complex additives of asphalt and asphaltite used for the preparation was performed at the chemical laboratories of IOTT and BashNII NP according to generally accepted methods.

The physicochemical properties of the mixtures were determined in accordance with GOST 23409.026-78. The value of thermal stresses according to Dietert was determined on a device mod. 705 f. Diter on hollow samples with a diameter of 28 mm and a length of 50 mm as a force,

necessary to prevent the expansion of the sample of the test mixture at 1000 ° C, referred to the cross-sectional area of the sample.

Anti-suppressant effect of supplements

was evaluated by strength in the moisture condensation zone of the molding mixtures prepared with their use on an SPNF f device. T. Fisher. To determine this indicator, mixtures were prepared including

5.0 wt.% Activated Dashukovsky bentonite, a complex additive in an amount equivalent to brilliant carbon yield 3.0% coal, the rest is silica sand 061K02B. The moisture content of the mixtures corresponded to a compaction of 60%.

For a comprehensive assessment of the non-stick-anti-burn-out properties of the additives, technological samples of the Benish type were cast — castings of cast iron weighing 10 kg.

From the data of table 4 it follows that the proposed complex additive compared with the additive selected as a prototype, has a significantly higher anti-suppressant effect and

causes a significant improvement in the physico-mechanical and technological properties of mixtures.

The implementation of the invention will improve the quality of the molding sand by increasing their anti-cracking effect, reducing gas production, and obtaining an economic effect by reducing the cost of cleaning castings and casting losses.

Table 1

No. N n / n

Additive Properties

The compressive strength in the wet state,

kgf / cm2

Tensile strength in the condensation zone

l

moisture, gf / cm Tightness,%

The value of thermal stresses according to the method of Dietert, kgf / cm2

Glossy carbon yield. %

The area of the lesion with the eyelets of the technological sample,%

 An increase or decrease in the content of additive components by less than 5.0% does not significantly affect its properties.

Table 4

table 2

Property metrics

0.75

16.0 47.0

5.6 0.30

37-40

Table 3

Claims (1)

The claims COMPREHENSIVE ADDITIVE FOR MANUFACTURE OF SAND-HL SHEET FORMING MIXTURES, including ground uyul with a low temperature of the beginning of softening, characterized in that ohm additionally contains asphaltite - a material obtained by selective 4 attraction (deasphalting) of resinous-asphaltene substances from residual products of oil distillation, with the following ratio of ingredients, wt.%: Asphaltite 15.0-60.0 Low temperature milled coal