Investigation of the effect of vacuum on the curing of mixtures on a silicate binder

The article presents the results of a study of the effect of vacuuming on the curing processes of liquid‑glass mixtures. The method of conducting experiments using an original laboratory vacuum installation and the mechanisms of curing a liquid‑glass mixture with various hardening methods are described. Studies have shown that vacuuming can signifi antly accelerate the curing and increase the strength of the mixture while reducing the content of the silicate binder. This; in turn; facilitates the knockability of liquid‑glass mixtures and expands the prospects for using these environmental friendly mixtures in foundry as an alternative to sands based on organic binders.

УТИЛИЗАЦИЯ ОТХОДОВ ГОМЕЛЬСКОГО ХИМИЧЕСКОГО ЗАВОДА С ПОЛУЧЕНИЕМ ТОВАРНОЙ ПРОДУКЦИИ

Статья посвящена актуальной проблеме переработки техногенных отходов, образующихся на ОАО Гомельский химический завод . Одним из видов многотоннажных отходов является фосфогипс отход производства экстракционной фосфорной кислоты. Авторы приводят результаты исследований получения искусственного гипсового камня на основе нейтрализованного фосфополугидрата сульфата кальция отхода производства экстракционной фосфорной кислоты полугидратным способом. На основе экспериментальных данных установлена возможность замены импортного природного гипсового камня искусственным на основе фосфополугидрата сульфата кальция при производстве цемента на основе клинкеров белорусских цементных заводов и его влияния на гидратацию клинкерных минералов. Авторами рассмотрены результаты исследований еще одного вида техногенных отходов, образуемых на ОАО Гомельский химический завод кремнегеля, являющегося отходом производства фтористого алюминия. Сдерживающим фактором, ограничивающим его использование, является высокая влажность, достигающая 70 . В статье приводятся результаты исследований получения на основе кремнегеля естественной влажности натрий- или калий-силикатного связующего, являющегося аналогом жидкого стекла. Показана возможность получения натрий- или калий-силикатного связующего безварочным способом, что позволяет значительно сократить энергозатраты на технологический процесс за счет исключения стадии варки силикат-глыбы, которая является обязательной в традиционной технологии получения жидкого стекла (натриевого или калиевого). Авторы приводят результаты исследований, показывающие возможность получения на основе натрий- или калий-силикатного связующего на основе кремнегеля окрасочных покрытий для силикатного кирпича. В качестве красителей при проведении исследований использовали минеральные пигменты на основе оксидов железа: желтый железоокисный и красный железоокисный и их сочетание. Установлено, что получаемое окрасочное покрытие является морозо- и атмосферостойким.The article is devoted to the actual problem of processing of man-made waste generated by JSC Gomel chemical plant. One of the many types of tonnage of waste is phosphogypsum waste production of wet-process phosphoric acid. The authors present the results of studies of artificial gypsum-based neutralized factological calcium sulphate waste production of wet-process phosphoric acid by the hemihydrate method. On the basis of the experimental data revealed the possibility of replacing imported natural gypsum artificial stone on the basis of phosphopantothenate of calcium sulfate in the production of cement based on clinkers Belarusian cement plants and its impact on the hydration of clinker minerals. The authors consider the results of studies of another type of man-made waste generated by JSC Gomel chemical plant - silica gel, which is a waste of aluminum fluoride production. The limiting factor for its use is high humidity, which reaches 70 . The article presents the results of studies on the basis of silica gel natural moisture sodium - or potassium-silicate binder, which is an analogue of liquid glass. The possibility of obtaining sodium - or potassium-silicate binder in a non-welding way, which can significantly reduce the energy consumption of the process by eliminating the stage of cooking silicate,which is mandatory in the traditional technology of producing liquid glass (sodium or potassium). The authors present the results of studies showing the possibility of obtaining on the basis of sodium - or potassium-silicate binder based on silica gel paint coatings for silicate bricks. Mineral pigments based on iron oxides: yellow iron oxide and red iron oxide and their combination were used as dyes in the research. It is established that the resulting coating is frost-and weather-resistant.

Acceleration of the Formation on the Sodium Silicate Binder in Investment Casting

For cost reduction of the molds manufacturing, as well as environmental load in foundries sodium silicate binder is often used. However, without treatment with special compositions that accelerate curing and improve their properties, sodium silicate molds have insufficient thermal spalling resistance and often cause the rejection of castings made of heat-resistant alloys. As a result of the research, there was developed a technology of chemical drying of the sodium silicate cover layers in investment casting with the use of aluminoborbophosphate concentrate. It allows to reduce the production time of ceramic molds by 2...3 times, as well as to increase their strength either before baking or after it by 20...25 %. At the same time, as a result of softening effect of aluminoborbophosphate concentrate after baking and cooling of the specimens there has been observed a significant reduction of their retained strength and, as a consequence, better knockout of fire-resistant shells. Industrial tests of the sodium silicate cover chemical drying showed a significant reduction of the investment castings rejection due to the insufficient thermal spalling resistance and the reduction of the cleaning processing time of casting made of heat-resistant alloys.

Accelerated Forming on the Sol-Silicate Binder in Precision Casting

As a result of the research, the technology of accelerated forming on the sol-silicate binder in precision casting has been developed. It is based on granular materials cladding by the gel-processing catalysts of the sol-silicate binder and on the use of the clad granular materials as the stucco of ceramic coating layers. That allows to achieve a reduction of ceramic molds product cycle of more than 2...2.5 times and strength improvement of 1.4...1.5 times at the temperature of baking. The developed technology allows to improve the quality of ceramic molds and significantly shorten the forming cycle. Production tests of the gel-processing clad stucco in the investment casting showed a significant reduction of the reject precision castings, acceleration of ceramic molds production and a reduction of the working hours on removing "wedged" ceramic from less-accessible cast section cavities of the pump parts from complex alloyed steels.