\begin{center}
    \begin{tikzpicture}
        \draw[step = 0.5cm, gray, very thin] (-7.25, -2.25) grid (7.25, 0.25);

        \node[separator, /separator= sifter] (A) at (-6.0, -0.75) {};
        \node[anchor = south] at (-6.0, 0.25) {\textbf{sifter}};

        \node[separator, /separator= impact] (A) at (-2.0, -0.75) {};
        \node[anchor = south] at (-2.0, 0.25) {\textbf{impact}};

        \node[separator, /separator= gravity] (A) at (2.0, -0.75) {};
        \node[anchor = south] at (2.0, 0.25) {\textbf{gravity}};
        
        \node[separator, /separator= wet scrubber] (A) at (6.0, -0.75) {};
        \node[anchor = south] at (6.0, 0.25) {\textbf{wet scrubber}};
    \end{tikzpicture}
    \\[0.25cm]
    \begin{tikzpicture}
        \draw[step = 0.5cm, gray, very thin] (-7.25, -2.25) grid (7.25, 0.25);

        \node[separator, /separator= spray] (A) at (-6.0, -0.75) {};
        \node[anchor = south] at (-6.0, 0.25) {\textbf{spray}};

        \node[separator, /separator= electrostatic] (A) at (-2.0, -0.75) {};
        \node[anchor = south] at (-2.0, 0.25) {\textbf{electrostatic}};

        \node[separator, /separator= electromagnetic] (A) at (2.0, -0.75) {};
        \node[anchor = south] at (2.0, 0.25) {\textbf{electromagnetic}};
        
        \node[separator, /separator=permanent magnet] (A) at (6.0, -0.75) {};
        \node[anchor = south] at (5.7, 0.25) {\textbf{permanent magnet}};
    \end{tikzpicture}
    \\[0.25cm]
    \begin{tikzpicture}
        \draw[step = 0.5cm, gray, very thin] (-7.25, -2.25) grid (7.25, 0.25);

        \node[separator, /separator= cyclone] (A) at (-2.0, -0.75) {};
        \node[anchor = south] at (-2.0, 0.25) {\textbf{cyclone}};

        \node[separator, /separator= venturi] (A) at (2.0, -0.75) {};
        \node[anchor = south] at (2.0, 0.25) {\textbf{venturi}};
    \end{tikzpicture}
\end{center}
