RU2259340C1 - Method of mixing explosive composition components and molding articles therefrom - Google Patents

Abstract

FIELD: explosives.

SUBSTANCE: invention relates to mixing explosive compositions and molding articles therefrom using jet molding technique. Method comprises dispensing second-type powdered oxidant into premixer by means of feeder with preset rotation frequency at working dispensers of viscous-liquid and powder-like components, stirrers, screw, and open gate in circulation stockline of premixer after admittance of the first half of working charge of premixer consisted of composition based on the first-type powdered oxidant, after which charged composition is stirred in premixer and simultaneously circulates in circulation stockline after admittance of the working charge of premixer and then products are molded under loading control on stirrer drives in premixer and vacuum mixer.

EFFECT: ensured safe operation and increased solidity of molded products.

1 dwg, 2 tbl, 10 ex

Description

The invention relates to the field of mixing explosive compositions and molding products from them, and in particular to a technology for mixing components containing two types of powdery oxidizing agents, and molding products by injection molding using a three-stage continuous mixer. The method can be applied to create technological processes for preparing a mixture of components of explosive compositions containing, like plastics, cured polymers and fillers.

An analysis of domestic and foreign literature found that there is a known method of manufacturing a charge from mixed solid fuel (US patent No. 3296043 class. 149-19), providing for the continuous supply of components to the mixer, mixing them, evacuating the fuel mass and molding the charge by injection molding.

It is known in technology (Kasatkin AG The main processes and apparatuses of chemical technology. Moscow, 1973, p. 259) the use of a circulation pump to intensify the displacement process and improve the uniformity of the distribution of the mixed components.

Also known is a method of manufacturing a charge of mixed solid rocket fuel (RF patent No. 2198864), which is adopted by the authors as a prototype, providing for simultaneous portioned dosing of powdered and liquid-viscous components into a mixer — an attachment along three autonomous lines, mixing in continuous mixers — an attachment mixer, pre-mixer and charge molding under pressure with remote control of the loading of the mixers.

In this method, a powdery oxidizing agent with additives is fed from the drive with a lock to a batch weight batcher, dosed in portions of 4-14 kg with an interval of 20-60 s. The flow pulsations are smoothed out, for which the powdery oxidizing agent is continuously sieved through a separator and fed with a transport screw to the mixer-attachment. Liquid viscous components (binder mixture and hardener mixture) are dosed in portions along two corresponding autonomous lines simultaneously supplying a powdery oxidizing agent to the mixer-set-top box. Component streams are continuously mixed and averaged in a cascade of three sequentially installed continuous mixers with adjustable loading and screw discharge: first, the powder oxidizer is wetted with liquid-viscous components in a prefix mixer with a load of 20-100 kg, then preliminary mixing and averaging are carried out in a preliminary mixer with a load of 600-750 kg and final mixing under vacuum in a vacuum mixer with a load of 150-350 kg with remote control of the load of mixers.

The use of this method for mixing explosive compositions containing two types of powdery oxidizing agent is impossible, since the method does not provide a dosing line for the second type of powdery oxidizing agent. Dosing of two types of powdery oxidizing agent on the same line is unacceptable due to the formation of hazardous mixtures sensitive to mechanical stress. In addition, the method does not provide for safe pre-wetting and mixing of components of an explosive composition containing two types of powder oxidizing agent.

The technical result of the present invention is the development of a method for safe mixing of components of explosive compositions and the manufacture of products containing two types of powder oxidizing agent by portion batching a pre-prepared sample of the second type of powder oxidizer in an autonomous line using a feeder with a tuned speed, mixing and circulation of the composition in the pre-mixer through the circulation mass pipe and molding during the control e and regulation of load on the drive agitators mixers.

The technical result is achieved by the fact that in the process of mixing the components of explosive compositions and forming compositions from them, including the simultaneous dosing of powdery and liquid-viscous components along autonomous lines, mixing the components in continuous mixers: mixer-prefix, pre-mixer, vacuum mixer and molding products under pressure two types of powdery oxidizing agents are used as powder components; after the first half of the working load has been recovered, precede mixers of the composition based on the first type of powdery oxidizing agent with the dispensers of liquid-viscous and powdery oxidizing agents, stirrers, auger and an open shutter on the circulating mass line supplied with the pre-mixer, start batch dosing into the preliminary mixer with the circulation mass line of a pre-prepared sample of the second type of powder oxidizer using feeder with a tuned speed and continue dosing until a full workload is set before cooking mixer. After this, the dosage of the components is stopped and the composition is mixed while circulating in the pre-mixer with the circulation mass pipe for 10-30 minutes, then the shutter in the circulating mass pipe is closed, a vacuum is created in the vacuum mixer, the shutter is opened in the vacuum mixer, when the mixers are working, they are filled in the vacuum mixer to full working load and form the product by unloading the composition from the preliminary and vacuum mixers to loads on the drives of the mixers 5-10% higher than the load and idling, whereupon the composition in the cycle is set premixer and molding is repeated.

An example of the hardware design of this method is shown in the diagram (drawing), where 1 is a pre-mixer, 2 is a dispenser of liquid-viscous components, 3 is a dispenser of a powdery oxidizer of the first type, 4 is a dispenser of a powdery oxidizer of the second type with a feeder, 5 is a mixer of a pre-mixer, 6 - auger of the preliminary mixer, 7 - shutter of the circulating mass pipe, 8 - circulating mass pipe, 9 - dispenser of additives (hardener, etc.), 10 - vacuum mixer, 11 - shutter of the vacuum mixer, 12 - mixer of the vacuum mixer.

In the process of molding products using continuous mixers, one of the main conditions for ensuring the safety and quality of mixing the components of the explosive composition is the synchronous dosing of component flows along autonomous lines into the mixer-set-top box in a strictly specified ratio. Thus, at the pre-mixing stage, complete wetting of the powdery oxidizer with liquid-viscous components is achieved, excluding the ingress of the wetted powdery oxidizer into the working area of the auger of the pre-mixer.

In the proposed method for mixing the components of explosive compositions containing two types of powder oxidizer, this problem is solved by portioning the second powder oxidizer in an autonomous line into the pre-mixer using a feeder with a configured frequency after filling the first half of the pre-mixer working load with a composition based on liquid-viscous components and the first powder oxidizing agent. Dosing the second powdery oxidizing agent into the pre-mixer until the first half of the mixer loading is set does not exclude the possibility of the non-wetted second powdery oxidizing agent getting into the working area of the screw of the preliminary mixer, which reduces the safety of the process of mixing the composition.

The uniformity of the distribution of the second powdered oxidizing agent of the explosive composition in the pre-mixer is ensured by mixing and circulating the composition through the circulating mass line during the recruitment of the second half of the charge and by additional circulation of the composition after recruiting the full working load of the pre-mixer.

When unloading the composition to the stage of forming products with small loads of preliminary and vacuum mixers, the possibility of air leakage into the vacuum zone from the side of the screw of the vacuum mixer and the violation of monolithic products are not ruled out. To ensure the integrity of the products in the proposed method provides for the formation of products to be carried out with constant monitoring and regulation of the loads on the drive of the mixer mixers. Unloading of the composition is carried out to loads on the drives of the mixer mixers, 5-10% higher than the load idling.

Examples of specific performance of the method are shown in tables 1, 2.

The homogeneity of the distribution of the components (mixing of the composition) was evaluated by achieving the minimum steady-state loads on the drive of the mixers, i.e. the composition is considered to be mixed when the loads on the drive of the mixers reach a minimum stable value.

From the data table. 1 it follows that the stabilization of the loads on the drive of the mixers of the pre-mixer is achieved after mixing and circulation for 10 minutes (option 3). Stirring the composition for more than 30 minutes lengthens the production cycle, increases costs. Thus, the optimal time for mixing the composition in the pre-mixer, providing high-quality mixing, is 10-30 minutes.

From the data table. 2 it follows that in the range of loads on the drive of the mixers of the preliminary and vacuum mixers, 5-10% higher than the idle load, high-quality molding of products with a minimum amount of composition residue in the mixers is ensured (option 6-8). When the composition is developed before the loads on the drive of the mixers are 4.5% higher than the idle loads, air is sucked into the vacuum zone from the side of the screw of the vacuum mixer and the formation of defects in the product (option 9). When the composition is developed before the loads on the drive of the mixers are 12.5% higher than the idle loads, the amount of composition residues in the mixers increases, the utilization factor of the working load of the mixers decreases (option 10).

The method of mixing the components of explosive compositions and molding products with positive results from them was tested under the conditions of the pilot production of FSUE NIIPM. The method provides a safe and high-quality mixing of components, molding of high-quality products in terms of solidity.

Table 1. The dependence of the loads on the drive of the mixer of the pre-mixer from the mixing time of the composition Options Duration of mixing, min. Loads on a drive of mixers of a preliminary mixer, kW: Result one 5 5.35 The loads on the drive of the mixers did not reach the minimum value, the composition is not mixed 2 8 3.85} 3 10 3.45 A stable minimum load on the drive of the agitators was achieved; 4 thirty 3.44} 5 35 3.45

Table 2. Change of loads on the drives of the mixers at the end of the unloading of the composition from the preliminary and vacuum mixers Options Idling loads on the drive of mixers, kW Loads at the end of unloading on drives of mixers minus idle loads, kW (%) Result pre-mixer vacuum mixer pre-mixer vacuum mixer 6 0.6 0.5 0.03 (5.0) 0.025 (5.0) High-quality molding of products by solidity is provided. 7 0.6 0.5 0.045 (7.5) 0.038 (7.5)} 8 0.6 0.5 0.06 (10) 0.05 (10) nine 0.6 0.5 0.027 (4.5) 0.022 (4.5) Air leaks into the evacuation zone 10 0.6 0.5 0.075 (12.5) 0.063 (12.5) The amount of the remainder of the composition increases.

Claims (1)

The method of mixing the components of explosive compositions and molding products from them, including simultaneous batch dosing of powdery and liquid-viscous components along autonomous lines, mixing the components in continuous mixers: mixer-prefix, pre-mixer, vacuum mixer and molding products under pressure, characterized in that As the powder components, two types of powder oxidizing agents are used, after the first half of the working load is recovered, pre-mix I composition based on the first type of powdery oxidizing agent with the dispensers of liquid-viscous and powdery oxidizing agents, stirrers, auger and an open shutter on the circulation mass pipe supplied with the pre-mixer, start batch dosing into the pre-mixer with the circulation mass pipe of a previously prepared sample of the second type of powder oxidizer using a feeder with a set speed and continue dosing until a full workload is set pre-loaded with mixer, after which the dosing of the components is stopped and the composition is mixed with simultaneous circulation in a preliminary mixer with a circulation mass pipe for 10-30 minutes, then the shutter on the circulation mass pipe is closed, a vacuum is created in the vacuum mixer, the shutter is opened on the vacuum mixer, when the mixers are working, they are filled into the vacuum mixer to a full working load and form the product by unloading the composition of the preliminary and vacuum mixers to the loads on the drives of the mixers 5-10% higher than m of idling load, after which the cycle of recruitment of the composition in the pre-mixer and molding products is repeated.