Primary explosives are highly sensitive materials that may explode even under only slight mechanical, thermic or electrostatic influence. They are mainly used in blasting caps, detonators and other means of ignition. Thus, they serve as initiators for all kinds of explosives within an ignition train.

The production of Lead Azide and Lead Trinitroresorcinate is carried out in a precipitation column using the continuous process developed by Meissner. This process is applied by various explosives manufacturers world-wide and is well proven with regard to its performance, product quality and safety.

During the past few years, Meissner has been able to improve the continuous as well as the discontinuous process essentially as far as automation and safety are concerned. Meissner has developed a modern plant conception which corresponds to the stricter safety regulations established by plant users and authorities or can at least be easily adapted.

Lead Azide

Depending on the kind of modification, Lead Azide is a white or slightly yellow solid material. During manufacture of the product, shape and size of the single crystals are specifically controlled in order to improve further processing. Lead Azide is a powerful primary explosive which in its pure form is very sensitive. In order to reduce the sensitivity and to modify the crystal shape, several additives are used for the production, among them dextrin, CMC, gelatine and others. Lead Azide is used in blasting caps, detonators and other means of ignition.

The production according to the Meissner process is performed continuously in a precipitation column. The starting solutions, Sodium Azide solution and a soluble lead salt, are separately dosed into the precipitation column by dosing pumps. The crystals resulting from the reaction are removed together with the mother lye at the bottom discharge valve. The mixture of crystals and mother lye is separated on a special filter, and the Lead Azide is washed with water and alcohol and dried thereafter. After the drying, the product is sieved and weighed in portions matching the requirements of further processing. All production steps are automated and can be operated by remote control which guarantees a high safety standard for the operator.

Lead Styphnate (Lead Trinitroresorcinate)

Lead Trinitroresorcinate (PbTNR) is obtained by converting Trinitroresorcinol (TNR) with lead salts. Depending on the formula and the reaction conditions, it is possible to generate various modifications of the product. Preference, however, is given to the neutral PbTNR which can be used as universal primary explosive. PbTNR is a constituent of priming compositions in priming caps (Sinoxide). Also, small quantities of PbTNR are mixed with Lead Azide in order to improve the ignition qualities of blasting caps.

PbTNR is produced according to the continuous Meissner process in a precipitation column. Since water solubility of TNR is quite low, TNR is dissolved as a magnesium salt and brought to reaction with a lead salt solution. The procedure is identical with the process described above for obtaining Lead Azide.

Tetrazene

Tetrazene is a white powdery product. It is not employed in its pure form, but represents an important component in a large number of ignition compositions because it has a high impact on the ignition sensitivity of those mixtures. Usually 2-5% of Tetrazene is added to the mixtures. Therefore the quantities being produced are that small that batch production is sufficient.

The starting materials for the production of Tetrazene are Aminoguanidine Sulfate (AGS) and Sodium Nitrite. The AGS solution is prepared in a heatable stainless steel vessel with stirrer and the Sodium Nitrite solution is added slowly. After being heated up to 40° C, Tetrazene begins to crystallize. After the crystallization process the composition is cooled down to room temperature and the product is filtered. After several washings the product is dried and portioned. In this process, too, the operator's contact with the product is reduced to a minimum.

Machines for Processing of Initiating Explosives

Additionally to plants for the individual explosives mentioned above, Meissner also offers equipment for mixing, loading and / or pressing for initiating mixtures. A fully automatic detonator loading and pressing machine is also within Meissner's scope of supply. In several successive work stations this machine provides loading and assembling of primary and secondary explosives in metal shells or caps. Depending on the design of the detonator, the capacity of this machine ranges from 500 to 1000 pieces per hour.

Sodium Azide

Sodium Azide can not be referred to as an primary explosive, but is an important starting material for manufacturing Lead Azide. Sodium Azide is used also in the automobile industry as a main component of gas generators for air bags. Sodium Azide is a white crystalline product, which dissolves in water very well. When being added to acids, Hydrazoic Acid is released which produces highly explosive azides with many different metals.

Meissner possesses the know-how for the production of Sodium Azide. While in the past metallic Sodium was converted with Ammonia to obtain Sodium Azide, which thereafter reacted with Dinitrogenmonoxide to Sodium Azide and Sodium Hydroxide, nowadays preference is given to a new process which is much more advantageous.

In this process, metallic Sodium is used as well which is converted with Ethyl Alcohol to Sodium Alcoholate. In a second step, Sodium Alcoholate is converted with Ethyl Nitrite to Sodium Azide and Ethyl Alcohol. Sodium Azide is separated from the mother lye, crystallized and is obtained in various qualities, depending on the respective further use. The Ethyl Alcohol is regenerated and returned into the process.

Styphnic Acid (Trinitroresorcinol)

Trinitroresorcinol (TNR) is, depending on its purity, a yellow or yellowish brown crystalline product. It is a weak explosive and serves as starting material for the production of the primary explosive PbTNR mentioned above.

For the production of TNR according to Meissner's process, Resorcinol is used as raw material. First Resorcinol is sulfonated and afterwards nitrated together with highly concentrated Nitric Acid to obtain Trinitroresorcinol. In a centrifuge the product is separated from the spent acid, washed several times, and stored in a water-wet state prior to further processing.