Abstract: A process for producing boron nitride is described, comprising reacting at least one boron compound selected from the group consisting of boric acid and metal salt thereof and at least one nitrogen-containing compound which is capable of bonding to the boron compound to form a compound in which a boron atom and a nitrogen atom co-exist, and then heating the compound thus formed at a temperature of at least 600.degree. C. in an atmosphere of inert or reducing gas. This process can produce high purity boron nitride at relatively low temperatures in high yields. Moreover, boron nitride can be obtained in desired crystal forms including a flake-like crystal form.

Abstract: A method for separating liquid drops of molten urea and/or a molten mixture of urea and its thermal decomposition product from an off gas that has been freed of melamine using at least two gas-liquid separators is disclosed. The method is characterized by filling the gas-liquid separator off stream or at rest with molten urea or a molten mixture of urea and its thermal decomposition product, and at the same time, forcing the molten liquid to flow within said gas-liquid separator to remove undesired melamine iso(cyanurate) therein.

Abstract: A lubricant containing an adduct of melamine and isocyanuric acid or cyanuric acid is effective for use in high-temperature, low-temperature, or high-pressure atmospheres, or places where black-color producing contamination is not desired, or in metal working, cutting or grinding of metals. The adduct not only functions as a solid lubricant but also as an agent to thicken liquid lubricants such as mineral oil, and it is used as a powder, or as suspended in a lube oil, grease or water, or it can be applied to surfaces subject to wear using a synthetic resin such as vinyl resin or epoxy resin as a binder.